Geotech_Study_-_Fire_Stations.pdf

APPENDIX A

GEOTECHNICAL STUDY

AND

APPENDIX B

FOUNDATION DESIGN ANALYSIS

GEOTECHNICAL STUDY

HOLLOMAN FIRE CRASH RESCUE STATIONS

HOLLOMAN AIR FORCE BASE

HOLLOMAN, NEW MEXICO

AMEC PROJECT NO. 6-517-000028

Submitted To:

Merrick & Company

5700 Harper Drive NE, Suite 400 Albuquerque, New Mexico 87109

Submitted By:

AMEC Earth & Environmental, Inc.

125 Montoya Road El Paso, Texas 79932

May 12, 2006

AMEC Earth & Environmental, Inc.

125 Montoya Road El Paso, Texas 79932 Tel (915) 585-2472 Fax (915) 585-2626 \www.amec.com

May 12, 2006 AMEC Job No. 6-517000028

Merrick & Company 5700 Harper Drive, N.E., Suite 400 Albuquerque, New Mexico 87109

Attn.: Mr. Jim Oschwald

Re: Geotechnical Study

Holloman Fire Crash Rescue Stations Holloman Air Force Base Alamogordo, New Mexico

Dear Mr. Oschwald:

AMEC Earth & Environmental, Inc. (AMEC) submits this Geotechnical Report for the above referenced project. The report includes the results of test drilling and laboratory analyses and presents recommendations for foundation design, slab support, paving and related earthwork.

Should any questions arise concerning this report, we would be pleased to discuss them with you.

Respectfully submitted, AMEC Earth & Environmental, Inc. Reviewed by:

David A. Varela, P.E. Ralph Crockett, P.E.

Geotechnical Project Engineer Senior Geotechnical Engineer

Copies: Addressee (3)

TABLE OF CONTENTS

REPORT Page

Introduction

Proposed Construction

Soil Study

Site Conditions and Geotechnical Profile

Discussion and Recommendations

APPENDIX A

Test Drilling Equipment and Procedures ................................................................................. A-1

Unified Soil Classification........................................................................................................ A-2

Terminology Used to Describe the Relative Density, Consistency or Firmness of Soil ................................................................................ A-3

Soil Moisture Classification ..................................................................................................... A-4

Site Plan ................................................................................................................................. A-5

Logs of Test Borings ............................................................................................................... A-6

APPENDIX B

Classification Test Data .......................................................................................................... B-1

APPENDIX C

Specifications for Earthwork....................................................................................................C-1

AMEC Job No. 6-5170000028

Geotechnical Study – Holloman Fire Crash Stations AMEC Project No. 6-517000028 Page (1)

1.0 INTRODUCTION

This report is submitted pursuant to a geotechnical study made by this firm for three proposed fire stations planned for construction at Holloman Air Force Base, New Mexico. The objective of this study was to evaluate the physical properties of the soil underlying the sites to provide recommendations for foundation design, slab support, paving and related earthwork.

2.0 PROPOSED CONSTRUCTION

Details of the project were provided to AMEC by Mr. Jim Oschwald of Merrick & Company.

It is our understanding that three new fire rescue stations are planned for construction at Holloman Air Force Base. The stations will be constructed with administration areas, as well as, high bay apparatus bays. The administration areas will be single-story structures constructed with either conventional steel framing with concrete masonry unit (CMU) load bearing walls or light-gage trusses supported by light-gage steel stud walls and CMU veneer. The apparatus bays will consist of steel moment frames supporting long-span joists. The structures will have sloped metal roofs. No basements are planned and slab-on-grade construction is anticipated.

The planned construction of the structures is assumed to consist of shallow spread and continuous type footings. Foundation loads for the proposed structures are unknown, but are not expected to exceed 100 kips on columns and 3 kips per lineal foot on walls. Cuts and fills for site grading are not expected to exceed 2 feet in depth to achieve finished grades.

Should final design details vary significantly from those outlined above, this firm should be notified for review and possible modification of recommendations.

3.0 EXPLORATORY STUDIES

3.1 RESISTIVITY SURVEY

Four pin Wenner resistivity arrays were performed at each of the sites. The surface resistivity lines were conducted with electrode spacings of 2.5, 5, 10 and 15 feet. The results of the four pin Wenner array studies are presented in Section 5.7.

3.2 SUBSURFACE EXPLORATION

Exploratory borings were advanced at each of the proposed fire station locations to a depth of 20 feet below existing grades. At each site, one boring was extended to a depth of about 80 feet below existing grade to evaluate soil conditions for the site seismic soil profile. Borings B-1

Geotechnical Study – Holloman Fire Crash Rescue Stations

Page (2) through B-19 were drilled at Fire Station 1, Borings B-20 through B-25 were advanced at Fire Station 2 and the remaining Borings B-26 through B-32 were drilled at Fire Station 3.

All test borings were drilled using a CME 75 truck mounted drill rig equipped with 8¼ inch O.D.

hollow stem augers. Standard penetration testing was performed at selected intervals in the borings. During the field study, the soils encountered were continuously examined, visually classified and logged. Results of the field study are presented in Appendix A, which includes a brief description of drilling and sampling equipment and procedures, site plans showing the boring locations and logs of the test borings.

The boring logs and related information included in this report are indicators of subsurface conditions only at the specific locations and times noted. Subsurface conditions, including groundwater levels, at other locations of the subject sites may differ significantly from conditions, which exist at the sampling locations.

3.3 LABORATORY ANALYSIS

To aid in soil classification and evaluate the engineering properties of the soil, selected soil samples were tested for moisture content, Atterberg limits, particle size testing and density tests. Laboratory tests were performed in general accordance with test standards ASTM D 2216, ASTM D 4318, ASTM D 422 and ASTM D 2937. The results of the moisture testing and density tests are presented in the boring logs found in Appendix A. Atterberg limits and particle size testing results are presented in Appendix B. In addition, selected soil samples were tested for sulfates, chlorides, pH and resistively to evaluate the corrosion potential of the soils encountered. Results of the testing are presented in Section 5.8 of the report.

The soils encountered during the field study were classified in general accordance with the Unified Soil Classification System. The soil classification symbols appear on the boring logs and are briefly described in Appendix A.

4.0 SITE CONDITIONS & GEOTECHNICAL PROFILE

4.1 SITE CONDITIONS

Fire Station 1

At present, a portion of the project site is improved with an asphalt parking lot. The remaining portion of the site was occupied by a structure, which was demolished. Several existing buried utility lines are present on the site. The topography of the site generally slopes to the south and east. Vegetation on the site consists of several large pine trees and landscaping gravel.

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Fire Station 2

The project site is currently improved with a hanger structure, asphalt pavement and existing water and gas utility lines. The topography of the site gradually slopes to the north with about 2 feet of relief across the property. Vegetation on the site generally consists of a sparse growth of grass and weeds.

Fire Station 3

At present, the project site consists of an undeveloped tract of land located along Periphery Road. The topography of the site is nearly level with a site elevation of about 4,086 feet, based on a grading and drainage plan provided to AMEC for review. Vegetation on the site generally consists of a moderate growth of grass and weeds with several medium sized bushes.

At one boring location B-30, suspected fill was encountered at about 5 feet, based on the presence of asphalt debris at about 5 feet below existing grade. Debris was not encountered at any of the remaining sampling locations placed at the site.

4.2 GEOTECHNICAL PROFILE

Fire Station 1

Soils encountered at the proposed Fire Station 1 location generally consist of three soil strata.

The upper soil stratum consists of a nonplastic to low plasticity silt and clayey silt with gypsum.

The moderately firm to firm soils extend from the ground surface to depths varying from 2 to 10 feet. Laboratory tests indicate liquid limits varying from 12 to 31 with corresponding plasticity indices of 3 to 14 for the fine-grained soils.

An intermediate soil stratum consisting of a nonplastic silty sand with gypsum was encountered directly below the surface silt and clayey silt layer extending to depths varying from 8 to 12 feet.

At Boring B-8, the nonplastic silty sand was observed to extend from the ground surface to a depth of about 12 feet. In addition, at Boring B-18, the silty sand was observed to extend from about 8 feet to the full depth of the boring. The relative density of the silty sand ranges from medium dense to dense based on standard penetration tests.

The third soil stratum consists of a low plasticity clay with gypsum that was encountered below the silty sand, extending to the full depths of the test borings (20 feet). Based on standard penetration tests, the lean clay soils were observed to have a moderately firm to hard consistency.

Boring B-9 was extended to a depth of about 80 feet below existing grade. Soils encountered within the upper 20 feet at the boring location are consistent with the descriptions presented above. Below a depth of 20 feet extending to the full depth of the boring, the soils encountered

Page (4) consist of a nonplastic silty sand, clayey sand and clay. The nonplastic silty sand was encountered at 20 feet extending to about 27 feet below the ground surface. A low plasticity clayey sand was observed below the sand extending to approximately 60 feet. A second silty sand layer from about 60 to 68 feet overlies a low plasticity sandy clay, which extends to the full depth of the boring.

Fire Station 2

As the exploratory borings indicate, the soils underlying the Fire Station 2 site generally consist of a lean clay, clayey silt and clayey sand with gypsum. Laboratory tests indicate liquid limits varying from 19 to 50 with corresponding plasticity indices of 3 and 29 for the clay soils. The consistency of the clay soils, based on standard penetration tests, generally ranges from moderately firm to very firm.

At Borings B-21 and B-25, an interbedded, nonplastic silty sand with gypsum was encountered within the soil profile. The medium dense to dense silty sand was generally observed at approximately 2 to 10 feet and from the ground surface to approximately 15 feet at Borings B-21 and B-25, respectively.

Boring B-22 extended to a depth of 80 feet below the ground surface to evaluate the site seismic profile. Soils encountered at the deep boring location generally consist of silty clay and clayey sand with gypsum. A high plasticity clay layer was encountered at about 25 to 40 feet below the ground surface. In addition, an interbedded silty sand layer was observed at about 70 to 80 feet below the ground surface.

Fire Station 3

As indicated in the exploratory borings, the soils underlying the Fire Station 3 site consist of low plasticity clays, clayey silts and silts with gypsum. These fine-grained soils generally extend from the ground surface to the full depths of the test borings. Laboratory tests indicate liquid limits varying from 18 to 40 with corresponding plasticity indices of 3 and 12 for the clay.

Consistency of the clay soils, based on standard penetration tests, generally ranges from moderately firm to very firm

In addition, interbedded clayey sands and silty sands with gypsum were encountered within the soil profile at depths varying from 2 to 4 feet below the ground surface extending to depths ranging from 7 to 15 feet. The clayey sands were observed to have a low plasticity with plasticity indices varying from 6 to 16. At Borings B-27, B-28, and B-29, gravel seams were encountered at approximately 5 and 10 feet below the ground surface.

Boring B-30 was extended to a depth of about 80 feet below existing grade to observe soils to evaluate the seismic site profile. Soils encountered at the boring location generally consist of low plasticity clay and clayey silts with gypsum as previously encountered at the other boring

Page (5) locations. Interbedded silty sand layers were also observed at about 2 to 8 feet and 33 to about 42 feet at the boring location.

4.3 SOIL MOISTURE AND GROUNDWATER CONDITION

At the time of our field studies, groundwater was encountered at each of the fire station sites at varying depths below existing grades. Based on our experience within the project area, groundwater fluctuations of 1 to 2 feet are possible. A summary of groundwater depths and soil moisture contents is provided below.

At Fire Station 1, groundwater was observed at the boring locations ranging from 11 to 18 feet below the ground surface. At several boring locations, a suspected perched groundwater was observed at about 4 to 9 feet below the ground surface. The perched groundwater layer was generally encountered within a relatively permeable silty sand stratum. Soil moisture contents above the water table were found to range from 3 to 19 percent.

At Fire Stations 2 and 3, groundwater depths encountered at the boring locations generally ranged from about 18 to 20 feet below the ground surface. Soil moisture contents above the water table were found to be damp to moist ranging from 3 to 37 percent.

5.0 DISCUSSION AND RECOMMENDATIONS

5.1 ANALYSIS OF RESULTS

Based on the results of the field and laboratory testing, the soils underlying the sites will provide reliable support of the proposed structures with some soil improvements. Following the recommended soil improvements, the proposed structures may be supported on spread and continuous type footings bearing on improved native soils or structural fill. Alternative methods for foundation support are available for the project such as mat-type and deep foundation systems. However, based on the soil conditions encountered at the project sites, it is our opinion that conventional shallow foundation systems will provide reliable support of the structures and provide the best economy for the projects. Should recommendations for an alternative foundation support be desired, AMEC can provide additional recommendation upon request.

It should be noted that some risk is involved with the recommended shallow foundations.

Should a broken water line or other source of moisture occur, some movement of slabs and foundations is possible. As a result, the recommendations concerning site drainage and moisture protection presented in Section 5.4 are considered critical for the satisfactory performance of the proposed structures.

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5.2 SHALLOW FOUNDATIONS

Shallow spread or continuous type footings bearing at uniform depths below finished grade are recommended for support of the proposed structures. A shallow foundation system may be used provided the site preparation and moisture protection recommendations presented in this report are strictly followed. The recommended site preparation for each of the proposed structures is presented in the table below.

Building Site Recommended Site Preparation Net Allowable

Bearing Pressure (psf)

Fire Station 1 Borings B-1 to B-19

The native soil below the base of all foundation elements, should be over excavated to a depth of 36 inches. Excavations shall extend laterally a minimum of 2 feet beyond the edge of all footings. The base of the excavation should then be scarified to a depth of 8 inches, brought to within plus or minus 3 percent of optimum moisture content and compacted. Structural fill should then be placed in compacted lifts to final grade.

2,000

Fire Station 2 Borings B-20 to B-25

The native soil below the base of all foundation elements, should be over excavated to a depth of 12 inches. Excavations shall extend laterally a minimum of

1.5 feet beyond the edge of all footings. The base of the excavation should then be scarified to a depth of 8 inches, brought to within plus or minus 3 percent of optimum moisture content and compacted. Structural fill should then be placed in compacted lifts to final grade.

2,000

Fire Station 3 Boring B-26 to B-32

The native soils below the base of all foundation elements, should be scarified to a depth of 8 inches, brought to within plus or minus 3 percent of optimum moisture content and compacted. Structural fill should then be placed, as required, in compacted lifts to final grade.

2,500

At the time of our field studies, the project sites were observed to be partially developed or previous improvements were demolished. It is recommended that all earthwork activities be monitored for the presence of man made fills and debris related to past improvements. Any fill or debris encountered should be over excavated in it’s entirely and replaced with structural fill placed in compacted lifts.

The net allowable bearing pressure recommended for each structure applies to full dead plus realistic live loads and can be safely increased by one-third for temporary loads including wind or seismic forces.

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Compaction of the soil should be accomplished by mechanical means to obtain a density of not less than 95 percent of maximum dry density. Optimum moisture content and maximum dry density should be determined in accordance with ASTM D 1557.

For all structures, the minimum depths of footings should be 2 feet below the lowest adjacent finished grade for perimeter footings and 1.5 feet below finished floor slab elevation for interior footings. The minimum recommended width of spread and continuous type footings is 2.0 feet and1.5 feet, respectively.

In order to minimize the sensitivity of the structures to differential movements, footings and stem walls should be reinforced to allow for a degree of load redistribution should a localized zone of supporting soil become saturated. Stem walls should be positively separated from slabs by use of expansion joint material.

It is estimated that vertical movements of footings designed as recommended above will not exceed 1 inch for moisture contents of the native soil encountered during test drilling or compaction moisture contents introduced during construction. Differential movements are expected to be less than 75 percent of the total movement. Significant moisture increases above these values could result in additional movements. As a result, recommendations presented in Section 5.4 concerning site drainage and moisture protection are considered critical for the satisfactory performance of the proposed structures.

Based on our experience within the project area, compaction of the existing subgrade soils is anticipated to be difficult due to the fine-grained nature and elevated moisture conditions encountered. Elevated moisture conditions of the existing subgrade soils generally results in unstable conditions consisting of “pumping” soils.

If unstable conditions are encountered, uniform sized rock should be placed to build a dense base prior to the addition of any structural fill. The rock should be sound and have a diameter ranging from 4 to 8 inches. The rock should be placed in a minimum thickness of 12 inches and compacted. Additional rock should be added, as required, into the excavation until a firm base has been established. Compaction of the rock should be achieved using a heavy smooth drummed compactor without vibratory action. In addition, it is recommended that all rock materials used be angular or subangular to provide a higher degree of interlock within the soil matrix. Structural fill should then be placed in compacted lifts to final grade.

5.3 SITE GRADING AND SLAB SUPPORT

All site grading and fill placement should be performed in accordance with the requirements presented in Appendix C of this report. Structural fill specifications as well as compaction requirements are also detailed in Appendix C.

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Below slabs on grade, the native soils should be scarified to a depth of 8 inches, brought to within 3 percent of optimum moisture content and compacted. Structural fill should then be placed, as required, in compacted lifts to final grade. These recommendations will result in a subgrade preparation, which will provide adequate support for a lightly loaded slab-on-grade floor. Thus, the use of granular base for structural support of lightly loaded slabs is not considered necessary. However, a 4-inch course can be placed below the slab to provide a working surface.

Heavily loaded slabs cast directly on prepared subgrade should be designed using a modulus of subgrade reaction value of 175 pounds per cubic inch. This value can be increased to 300 pci provided a minimum of 6 inches of granular base is placed beneath the slab. Where granular base is used, it should meet the following grading requirements as determined in accordance with ASTM D 422:

Sieve Size (Square Openings)

Percent Passing by Dry Weight

1 inch ¾ inch

no. 4

no. 200

85 - 100 45 - 95 0 - 8

The granular base should have a plasticity index of no greater than 12 when tested in accordance with ASTM D 4318. The coarse aggregate should have a percent of wear, when subjected to the Los Angeles abrasion test (ASTM C 131), of no greater than 50. Granular base should be compacted to at least 95 percent of ASTM D 1557 maximum dry density.

Granular base will tend to act as a capillary barrier to moisture but will not provide a positive barrier against the rise of moisture to the slab. If the moisture sensitivity of floor coverings is considered critical, an impervious membrane vapor barrier should be placed beneath the floor slabs.

5.4 SITE DRAINAGE AND MOISTURE PROTECTION

The soils encountered at the project site were observed to contain a moderate to high gypsum content. The variable gypsum content within the soil matrix is soluble under elevated moisture conditions. The addition of appreciable moisture can produce a significant reduction in strength of the gypsum rich soil by creating voids or cavities. As a result, recommendations concerning site drainage and moisture protection of the soils presented below are considered critical to the satisfactory performance of the structures.

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Moisture increases in the soil supporting foundations would reduce their support value and increase foundation and slab movements. Therefore, positive site drainage should be provided during construction and carefully maintained for the life of the structures.

Where slabs or pavements do not immediately adjoin the proposed structures, the ground surface should be sloped away from the perimeter of the structures in a manner to allow flow along the drainage lines at a minimum grade of 5 percent to points at least 15 feet away.

Positive drainage should be provided from these points to streets or natural water courses. In no case should long-term ponding of water be allowed within 20 feet of the perimeter of the proposed structures.

No landscaped areas should be situated adjacent to the perimeter of the structures unless they are constructed in such a way as to prevent excess irrigation or storm water from infiltrating beneath the structures. All landscaped areas located near the structures should be constructed to allow any excess surface water to drain freely and rapidly away from the structures.

Landscaping near the structures should consist of short rooted, desert type plants that require little or no watering. Irrigation systems for vegetation located near the structures should be designed to deliver only the amount of water required by the plants. The irrigation systems should never be operated in a manner that could saturate or flood the landscaped areas.

Roof drains should be designed and constructed to discharge storm water directly onto paved areas that will carry the water rapidly away from the buildings. No storm water from roof drains should be allowed to discharge onto or accumulate in unpaved areas close to the structures.

The possibility of moisture infiltration beneath the proposed structures, in the event of plumbing leaks, should be considered in the design and inspection of underground water and sewer conduits. All backfill behind footings and stem walls as well as utility trench backfill within 15 feet of the structures should be compacted as recommended for structural fill in Appendix C.

Adequate site drainage should also be maintained during construction due to the sensitivity of the native soils to moisture creating unstable conditions. Additional site preparation may be required during periods of wet weather for the excavation of wet, unstable soils.

5.5 LATERAL LOADS

The pressure exerted on retaining walls will depend on their degree of restraint. Rigid, restrained walls with horizontal backfill meeting structural fill requirements as presented in Appendix C of the geotechnical report, should be designed using an "at rest" equivalent fluid pressure of 55 pounds per cubic foot (pcf). Walls allowed to rotate around their bases at a distance of 0.001 times their height or more, at the top, should be designed using an "active" equivalent fluid pressure of 40 pcf.

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The passive soil resistance against the edges of footings, stem walls, etc. with properly compacted backfill, should be considered as being equal to forces exerted by a fluid of 325 pounds per cubic foot unit weight. A coefficient of friction of 0.35 is recommended for computing lateral resistance between the bases of the footing and slabs and the soil in analyzing lateral loads.

The equivalent fluid pressures do not include any lateral component due to either hydrostatic or surcharge loads. The retaining walls at this site should be designed with a drainage system to prevent the build up of hydrostatic forces behind the wall. If a drain system is not provided, then an additional 62.4 pcf must be added to the lateral forces acting on the wall. Special care should be taken not to over compact the backfill material to reduce the potential for the build up of residual compaction pressures against the retaining walls.

The equivalent fluid pressures provided above do not include a factor of safety, however, we recommend that a minimum factor of safety of 1.5 be used for the design of retaining walls against overturning and sliding. Surcharge loads to the area adjacent to the retaining wall can add additional horizontal components of lateral earth pressures to this wall. The magnitude of these components will depend on the loads and locations of these loads relative to the retaining wall.

5.6 PAVEMENT RECOMMENDATIONS

5.6.1 FLEXIBLE PAVEMENT

An average traffic volume of ten 18-kip equivalent single axle loads (ESAL’s) per day has been assumed for the design of the pavement section. This assumption is based on the continuous use of driving areas by light automobile and heavy truck traffic. A Terminal Serviceability Index (Pt) value of 2.0 and an R value of 15 was used for purposes of design. A design life of 20 years was employed for the development of the pavement section under AASHTO Guidelines for Design of Pavement Structures and generally accepted civil engineering standards and practices.

Prior to construction of a flexible pavement section, the existing subgrade should be scarified to a depth of 8 inches, brought to within plus or minus 3 percent of optimum moisture content and compacted. The paved area should then be brought to final subgrade elevation with properly compacted structural fill as determined by drainage considerations and pavement thickness.

Structural fill should be non-expansive and meet specifications as outlined in Appendix C of this geotechnical report.

Following the proper treatment of the subgrade, a flexible pavement section consisting of 2 inches of asphaltic concrete overlying 8 inches of crushed aggregate base course should be constructed for light automobile traffic. In areas with heavy truck traffic, a flexible pavement

Page (11) section consisting of 3 inches of asphaltic concrete overlying 8 inches of crushed aggregate base course is recommended.

Asphaltic concrete materials quality and construction requirements should conform to Section 401 of the current New Mexico State Highway Department Standard for construction of Highways, Roads and Bridges. Mineral aggregate should comply with Grading B, Type II, Item

401.22. A job mix formula should be established using the Marshall method of mix design with a minimum stability of 1,600 pounds as determined in accordance with ASTM D 1559. The bituminous material and aggregate proposed for use in construction by the contractor should be used in the mix design. The asphaltic surface course should be placed in uniform thickness lifts with no single lift greater than 2 inches.

Aggregate base course should conform with the requirements of Type I-B or Type II-B of Section 304 of the New Mexico State Highway Department Standard for construction of Highways, Roads and Bridges.

5.6.2 RIGID PAVEMENT

For paved areas subjected to heavy truck traffic with regular stopping, starting or turning actions, a rigid pavement section is recommended in lieu of a flexible pavement.

Recommendations provided above for subgrade preparation should be followed prior to the construction of the rigid pavement section. These recommendations will result in a subgrade preparation that will provide adequate support for the rigid pavement section.

The concrete to be used in construction was assumed to have an elastic modulus of 3x106 psi and a mean modulus of rupture of 650 psi. This would correspond to a 28-day cylinder strength of 3,000 psi as determined in accordance with ASTM C 39. A working stress of 40,000 psi (corresponding to Grade 40) was assumed for the reinforcing steel.

Based on the above design parameters and guidelines provided by AASHTO (1986), a 78-inch concrete pavement slab is recommended. All materials and methodologies used in construction should conform with guidelines presented in Section 451 of the current New Mexico State Highway Department Standard for construction of Highways, Roads and Bridges. It is recommended the concrete slab is constructed to allow rapid drainage of surface runoff away from the soil directly underlying the pavement section.

5.7 RESISTIVITY SURVEY

Four pin Wenner array lines were performed during this study. Two surface resistivity lines were placed in a cross pattern at Fire Station 1 and 2 with electrode spacings of 2.5, 5, 10, 15 and 20 feet. At Fire Station 3, one surface resistivity line was placed at the site with an electrode spacing of 2.5, 5, 10, 15 and 20 feet. Raw data collected from the four pin Wenner arrays is presented in tables below.

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FOUR POINT WENNER ARRAY

FIRE STATION 1

Line 1

Spacing (ft)

Reading (ohm)

Approximate Resistivity (ohm*cm)

2.5 6.2 2374.6 5 7.6 727.7 10 5.5 1053.3 15 4.0 1149.0 20 3.5 1340.5

Line 2

(ft)

Reading (ohm)

Approximate Resistivity (ohm*cm)

2.5 6.2 2374.6 5 8.0 766.0 10 5.8 1110.0 15 4.3 1235.2 20 3.5 1340.5

FIRE STATION 2

(ft)

Reading (ohm)

Approximate Resistivity (ohm*cm)

2.5 7.6 2910.8 5 8.3 794.7 10 5.9 1129.9 15 4.2 1206.5 20 3.7 1417.1

Line 2

(ft)

Reading (ohm)

Approximate Resistivity (ohm*cm)

2.5 7.0 2681.0 5 8.8 842.6 10 5.0 957.5 15 3.2 919.2 20 2.2 842.6

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FIRE STATION 3

(ft)

Reading (ohm)

Approximate Resistivity (ohm*cm)

2.5 6.0 2298.0 5 8.3 794.7 10 6.1 1168.2 15 4.5 1292.6 20 3.8 1455.4

5.8 CORROSION POTENTIAL

As discussed previously, gypsiferious soils with a high sulfate content were generally observed within the soil profile at each of the project sites. These soils are known to be aggressive and pose a risk for corrosion in concrete and steel structures. Proper sulfate resistant concrete and corrosion protection of metal structures is therefore required for long-term performance.

Selected soil samples collected during the field study were submitted for analytical testing to evaluate the pH, chlorides and sulfate content of the soils. The results of the testing were not available at the time of this report and will be submitted as an addendum upon receipt.

5.9 SEISMIC CONSIDERATIONS

The project site is located in Seismic Risk Zone 1 of the Seismic Zone Map of the United States as indicated by the 2000 International Building Code. Based upon the nature of the subsurface materials, a seismic site class of SD should be used for the design of structures for the proposed project (2000 International Building Code, Table No. 1615.1.1).

6.0 CONSTRUCTION OBSERVATION AND TESTING

Recommendations presented in previous sections of this report are predicated on the fact that there will be continuous observation and testing by the geotechnical engineer during earthwork operations. Verification of recommended excavation, moisture increases, site grading and required degree of compaction should be performed in accordance with "Guide Specifications for Earthwork," Appendix C.

The recommendations presented in this report are based upon a limited number of subsurface samples obtained from widely spaced locations. The samples may not fully indicate the nature and extent of the variations that actually exist throughout the site. For that reason, among others, AMEC recommends that AMEC be retained to observe earthwork construction. It

Page (14) should be noted, if variations or other latent conditions become evident during earthwork construction, it will be necessary for AMEC to review these conditions and modify its recommendations.

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TEST DRILLING EQUIPMENT & PROCEDURES

SAMPLING PROCEDURES- Dynamically driven tube samples are usually obtained at selected intervals in the borings by the ASTM 0-1586 procedures. In most cases, 2" 0.0., 13Ja"1.0. samplers are used to obtain the standard penetration resistance. "Undisturbed" samples of firmer soil are often obtained with 3" 0.0. samplers lined with 2.42" 1.0. brass rings. The driving energy is generally recorded as the number of blows of a 140 pound, 30-inch free fall drop hammer required to advance the samplers in 6-inch increments. However, in stratified soil, driving resistance is sometimes recorded in 2 or 3-inch increments so that soil changes and the presence of scattered gravel or cemented layers can be readily detected and the realistic penetration values obtained for consideration in design. These values are expressed in blows per foot on the logs. "Undisturbed" sampling of softer soil is sometimes performed with thin walled Shelby tubes (ASTM 0-1587).

Where samples of rock are required, they are obtained in NX diamond core drilling (ASTM 0-2113).

Tube samples are labeled and placed in watertight containers to maintain field moisture contents for testing. When necessary for testing, larger bulk samples are taken from auger cuttings.

CONTINUOUS PENETRATION TESTS - Continuous penetration tests are performed by driving a 2" 0.0. blunt nosed penetrometer adjacent to or in the bottom of borings. The penetrometer is attached to 1%" 0.0. drill rods to provide clearance to minimize side friction so that penetration values are recorded as the number of blows of a 140 pound, 30-inch free fall drop hammer required to advance the penetrometer in one foot increments or less.

BORING RECORDS - Drilling operations are directed by our field engineer or geologist who examines soil recovery and prepares boring logs. Soil is visually classified in accordance with the Unified Soil Classification System (ASTM 0-2487), with appropriate group symbols being shown on the logs.

I-'

JI

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SOIL MOISTURE CLASSIFICATION

Group A - Coarse Grained Soils. nonplastic to plasticity index <7.

Includes: SM, SP-SM, SP, SW, GM, GP, and GW.

Group B - Fine Grained Soils to clayey sands & gravels with a plasticity index >7.

Includes: GC, SC, Ml, MH, Cl, and CH.

Dry Absence of moisture, dusty. Dry to the touch. I 0-4 I 0-8

Damp Grains appear slightly darkened, but no visible I 4-8 I 8-16 water. Silt/clay may clump. Sand will not bulk.

Soils are below plastic limits.

Moist I Grainsappeardarkened,butnovisiblewater. I 8-16 I 16-30

Silt/clay will clump. Sand will bulk. Soils are often at or near plastic limits.

Wet I Visiblewateron largergrainsurfaces.Sand I >16 I >30 and cohesionless silt exhibit dilatancy.

Cohesive silt/clay can be readily remolded.

"Wet" indicates that the soil is much wetter than the optimum moisture content and above the plastic limit (APL).

Water Bearing A water-producing formation. I N/A I N/A ame&

TERMINOLOGY USED TO DESCRIBE THE RELATIVE DENSITY,

CONSISTENCY OR FIRMNESS OF SOILS

The terminology used on the boring logs to describe the relative density, consistency or firmness of soils relative to the standard penetration resistance is presented below. The standard penetration resistance (N) in blows per foot is obtained by the ASTM D1586 procedure using 2" D.D., 1 3/8" I.D. samplers.

1. Relative Densitv. Terms for description of relative density of cohesionless, uncemented sands and sand-gravel mixtures.

~ Relative Densitv

0-4 I 5-10 11-30 31-50

I

50+1 I

Relative Consistelncv.

saturation.

Very loose Loose Medium dense Dense Very dense

2. Terms for description of clays which are saturated or near

Remarks

Easily penetrated several inches with fist.

Easily penetrated several inches with thumb.

Can be penetrated several inches with thumb with moderate effort.

Readily indented with thumb, but penetrated only with great effort.

Readily indented with thumbnail.

Indented only with difficulty by thumbnail.

3. Relative Firmness. Terms for description of partially saturated. and/or cemented soils which commonly occur in the Southwest including clays, cemented granular materials, silts and silty and clayey granular soils.

~ Relative Firmness

. 0-4 5-8 9-15 16-30 31-50 50+

Very soft Soft Moderately firm Firm Very firm Hard

.JL Relative Consistencv

0-2 Very soft 3-4 Soft 5-8 Medium stiff

9-15 Stiff

16-30 Very stiff 30+ Hard

TABULATION OF TEST RESULTS

DATE: March 31, 2006 AMEC JOB NO: 6-517-000028

PROJECT: Holloman AFB Fire/Crash Rescue Station

Holloman AFB New Mexico

SIEVE ANALYSIS - ACCUM. % PASSING

BORING

NO.

LOCATION

DEPTH

UNIFIED

CLASS.

LL

PI

3/8

1/2

3/4

1-1/2

MOISTURE

LAB

B1 See site plan 2½’ SC 12 3 43.1 63 94 99 99 100 9.6 67727-2 B2 See site plan 5’ ML NV NP 72.3 86 95 98 99 100 9.1 67727-3

B3 See site plan 5’ ML NV NP 64.3 87 92 97 99 100 15.8 67727-4

B4 See site plan ½’ ML NV NP 49.9 60 79 93 98 100 6.6 67727-5

B5 See site plan 5’ SM NV NP 39.4 66 76 99 100 7.2 67727-6

B6 See site plan ½’ ML NV NP 57.7 74 91 99 100 100 6.2 67727-7

B7 See site plan 5’ SM NV NP 28.7 58 67 99 100 3.5 67727-8

B8 See site plan 2½’ SM NV NP 26.0 63 94 99 100 3.9 67727-9

B9 See site plan 2½’ ML NV 1 53.5 70 91 96 98 100 13.2 67727-10

B9 See site plan 5’ SM NV NP 43.3 75 97 100 100 8.5 67727-11

B9 See site plan 35’ SC 19 2 38.0 58 84 96 98 99 100 -- 67727-12

B9 See site plan 60’ SM NV NP 28.4 78 96 97 99 100 -- 67727-13

B10 See site plan 2½’ ML NV NP 61.3 83 91 99 100 100 18.1 67727-14

B10 See site plan 5’ SM NV NP 37.2 67 90 98 99 100 14.7 67727-15

B10 See site plan 10’ CL 26 13 51.6 65 70 82 98 97 100 14.4 67727-16

B11 See site plan ½’ SC 21 10 48.1 63 81 87 90 92 95 11.8 67727-17

DATE: May 31, 2006 AMEC JOB NO: 6-517-000028

B11 See site plan 5’ ML NV NP 51.0 76 94 99 100 100 16.5 61127-18

B12 See site plan 2½’ CL 14 8 65.6 79 93 99 100 100 17.1 67727-19

B12 See site plan 5’ ML NV NP 58.8 83 97 99 100 100 14.2 67727-20

B12 See site plan 10’ SC 22 8 45.9 65 86 95 99 100 12.4 67727-21

B13 See site plan 5’ SM NV NP 39.2 58 83 93 96 99 100 17.4 67727-22

B14 See site plan ½’ ML NV NP 63.4 74 88 97 99 100 19.7 67727-23

B14 See site plan 5’ SM NV NP 46.6 68 88 96 99 100 16.2 67727-24

B15 See site plan 2½’ CL-ML 15 2 61.2 75 92 99 100 100 20.6 67727-25

B16 See site plan 2½’ ML NV NP 59.6 74 88 96 99 100 10.6 67727-26

B16 See site plan 10’ SM NV NP 34.3 53 80 92 97 100 13.7 67727-27

B17 See site plan 2½’ CL 31 14 61.8 73 90 99 100 100 15.0 67727-28

B17 See site plan 5’ CL 41 10 63.0 94 94 98 99 99 100 15.8 67727-29

B18 See site plan 2½’ CL-ML 35 3 61.6 76 91 96 98 100 15.9 67727-30

B19 See site plan ½’ SC 16 3 39.4 51 65 74 79 87 92 97 100 7.1 67727-31

B20 See site plan 10’ CL 26 10 72.0 84 90 95 98 100 29.1 67727-32

B21 See site plan 2½’ SM NV NP 35.0 41 52 64 73 77 100 30.8 67727-33

DATE: May 31, 2006 AMEC JOB NO: 6-517-000028

B21 See site plan 10’ 16.6 32 45 62 85 100 37.7 67727-34

B22 See site plan 2½’ CL 29 9 65.9 68 82 95 98 100 12.4 67727-35

B22 See site plan 5’ SC 19 3 8.8 13 58 89 94 100 25.4 67727-36

B22 See site plan 15’ CL 21 5 64.2 77 87 95 98 100 100 15.4 67727-37

B22 See site plan 25’ CH 50 29 60.5 64 76 91 96 100 27.4 67727-38

B22 See site plan 45’ CL 31 19 50.3 60 67 81 95 100 100 -- 67727-39

B23 See site plan 5’ ML NV NP 56.1 74 91 99 100 100 26.4 67727-40

B23 See site plan 10’ ML NV NP 59.6 61 83 89 99 100 16.3 67727-41

B24 See site plan ½’ SC 17 3 45.7 60 79 85 91 99 100 33.2 67727-42

B24 See site plan 5’ SM NV NP 34.5 36 74 98 99 100 9.2 67727-43

B25 See site plan 2½’ SM NV NP 17.1 28 45 54 62 82 91 100 -- 67727-44

B26 See site plan 2½’ CL 20 6 65.3 76 86 89 90 92 92 100 12.0 67727-45

B27 See site plan 5’ SC 21 6 42.8 53 66 75 82 88 90 100 8.0 67727-46

B28 See site plan 5’ SC 26 6 27.2 33 43 61 78 93 96 100 3.0 67727-47

B28 See site plan 10’ SM NV NP 33.0 46 87 100 100 -- 67727-48

B29 See site plan 2½’ CL 34 9 70.0 73 82 89 100 100 8.4 67727-49

DATE: May 31, 2006 AMEC JOB NO: 6-517-000028

B29 See site plan 5’ CL 34 12 75.8 86 97 100 12.0 67727-50

B29 See site plan 10’ SM NV NP 34.1 42 53 63 73 82 89 100 7.5 67727-51

B30 See site plan 2½’ SM NV NP 41.2 46 59 73 87 93 100 13.3 67727-52

B30 See site plan 10’ CL-ML 18 3 51.5 68 96 99 100 100 17.0 67727-53

B30 See site plan 20’ ML NV NP 60.5 84 89 91 95 100 18.6 67727-54

B30 See site plan 35’ SM NV NP 17.3 25 88 99 100 100 21.1 67727-55

B31 See site plan 2½’ CL-ML 18 3 63.8 69 81 95 99 100 27.7 67727-56

B31 See site plan 5’ CL 40 6 70.7 75 90 98 100 100 29.4 67727-57

B31 See site plan 10’ ML NV NP 69.5 74 92 99 100 28.2 67727-58

B32 See site plan 2½’ CL-ML 19 4 87.2 90 97 99 100 24.4 67727-59

B32 See site plan 5’ ML NV NP 52.7 71 96 99 100 100 4.0 67727-60

B32 See site plan 10’ CL-ML 22 3 73.6 79 92 99 100 28.7 67727-61

AMEC Project No. 6-517-000028 Page (C-1)

GUIDE SPECIFICATIONS FOR EARTHWORK

1. SCOPE

Includes all clearing and grubbing, removal of obstructions, general excavating, grading and filling and any related items necessary to complete the grading for the entire project in accordance with these specifications.

2. SUBSURFACE SOIL DATA

Subsurface soil studies have been made and the results are available for examination by the contractor. The contractor is expected to examine the site and determine for himself the character of materials to be encountered.

No additional allowance will be made for rock removal, site clearing and grading, filling, compaction, disposal or removal of any unclassified materials.

3. CLEARING AND GRUBBING

A. General: Clearing and grubbing will be required for all areas shown on the plans to be excavated or on which fill is to be constructed.

B. Clearing: Clearing shall consist of removal and disposal of vegetation observed during field activities. Clearing activities shall also include the complete removal of the existing structures and other improvements located on the project sites.

C. Grubbing: Stumps, matted roots and roots larger than 2 inches in diameter shall be removed from within 6 inches of the surface of areas on which fills are to be constructed except in roadways. Materials as described above within 18 inches of finished subgrade in either cut or fill sections shall be removed. Areas disturbed by grubbing will be filled as specified hereinafter for STRUCTURAL FILL.

4. EARTH EXCAVATION

A. Earth excavation shall consist of the excavation and removal of suitable soil for use as embankment as well as the satisfactory disposal of all vegetation, debris and deleterious materials encountered within the area to be graded and/or in a borrow area.

B. Excavated areas shall be continuously maintained such that the surface shall be smooth and have sufficient slope to allow water to drain from the surface.

Page (C-2)

5. STRUCTURAL FILL

A. General: Structural fill shall consist of a controlled fill constructed in areas indicated on the grading plans.

B. Materials:

(1) Physical Characteristics: Structural fill material shall consist of soil that conforms to the following physical characteristics:

Sieve Size Percent Passing

(Square Openings) by Weight

3 inch 100 3/4 inch 70 - 100

no. 4 40 - 100

no. 200 10 - 40

The plasticity index of the material, as determined in accordance with ASTM D 4318, shall not exceed 12. The fill material shall be free from roots, grass, other vegetable matter, clay lumps, rocks larger than 3 inches in any dimension, or other deleterious materials.

(2) Site Soil: Site soil from cuts may be used for fill, provided they meet the requirements in paragraph 5.B.(1). The results of this soil study indicate that most of the soils encountered at the site may not meet the requirements for structural fill. Some import materials or blending with an import material may be required.

(3) Borrow: When the quantity of suitable material required for embankments is not available within the limits of the jobsite, the contractor shall provide sufficient materials to construct the embankments to the lines, elevations and cross sections as shown on the drawings from borrow areas. The contractor shall obtain from owners of said borrow areas the right to excavate material, shall pay all royalties and other charges involved, and shall pay all expenses in developing the source including the cost of right-of-way required for hauling the material.

C. Construction:

(1) Building Area Treatment- Fire Station 1: The building pad shall be inspected by a representative of the geotechnical engineer prior to fill placement to verify clearing and grubbing.

The native soil underlying the base of all foundation elements shall be over excavated to a depth of 36 inches. Excavations shall extend laterally a minimum of 2.0 feet beyond the edge of all footings. The base of the excavation shall then be scarified to a depth of 8

AMEC Project No. 6-517-000028 Page (C-3) inches, brought to within plus or minus 3 percent of optimum moisture content and compacted. Structural fill shall then be placed in compacted lifts to final grade.

(1b) Building Area Treatment- Fire Station 2: The building pad shall be inspected by a

The native soil underlying the base of all foundation elements shall be over excavated to a depth of 12 inches. Excavations shall extend laterally a minimum of 1.5 feet beyond the edge of all footings. The base of the excavation shall then be scarified to a depth of 8 inches, brought to within plus or minus 3 percent of optimum moisture content and compacted. Structural fill shall then be placed in compacted lifts to final grade.

(1c) Building Area Treatment- Fire Station 3: The building pad shall be inspected by a

The native soil underlying the base of all foundation elements shall be scarified to a depth of 8 inches, brought to within plus or minus 3 percent of optimum moisture content and compacted. Structural fill shall then be placed, as required, in compacted lifts to final grade.

(2) Slabs on Grade Treatment: Site preparation shall consist of scarifying the native soils to a depth of 8 inches. The scarified soil shall then be brought to within plus or minus 2 percent of the optimum moisture content and compacted. Structural fill should then be placed, as required, in compacted lifts to final grade.

(3) Compaction: All fill shall be spread in layers not exceeding 8 inches, watered as necessary, and compacted. Moisture content at the time of compaction shall be within plus or minus 3 percent of the optimum moisture content. Compaction of the fill shall be accomplished by mechanical means only to obtain a density of not less than 95 percent of maximum dry density for the building pad, paved areas, and other structural areas.

Embankments outside the building pads shall be compacted to 90 percent of maximum dry density. Optimum moisture content and maximum dry density for each soil type used shall be determined in accordance with ASTM D 1557. Where vibratory compaction equipment is used, it shall be the contractor's responsibility to insure that the vibrations do not damage nearby buildings or other adjacent property.

Based on our experience within the project area, compaction of the existing subgrade soils is anticipated to be difficult due to the fine-grained nature and elevated moisture conditions encountered. To stabilize soils, uniform size rock shall be placed to build a dense base prior to the addition of any structural fill.

Page (C-4)

(4) Weather Limitations: Controlled fill shall not be constructed when the atmospheric temperature is below 35 degrees F. When the temperature falls below 35 degrees, it shall be the responsibility of the contractor to protect all areas of completed surface against any detrimental effects of ground freezing by methods approved by the geotechnical engineer.

Any areas that are damaged by freezing shall be reconditioned, reshaped and compacted by the contractor in conformance with the requirements of this specification without additional cost to the owner.

D. Slope Protection & Drainage: The edges of the controlled fill embankments shall be graded to the contours shown on the drawings and compacted to the density required in paragraph 5.C.(3). Slopes steeper than 1 vertical to 3 horizontal shall be protected from erosion.

6. INSPECTION & TESTS

A. Field Inspection & Testing: The owner shall employ the services of…