Exhibit B - Geo-Tech Report for Nearby Site.pdf

AIR FORCE TARGETING CENTER FACILITY

LANGLEY AIR FORCE BASE

HAMPTON, VIRGINIA

Revised Limited Subsurface Exploration and Preliminary

Geotechnical Engineering Report

January 2016

PREPARED BY:

Geo Environmental Section, Norfolk District U.S. Army Corps of Engineers Fort Norfolk, 803 Front Street Norfolk, VA 23510

INTRODUCTION

This report has been prepared by Norfolk District U.S. Army Corps of Engineers (NAO) to provide a general characterization of the subsurface conditions at the project site and provides a general overview of the soil and geologic conditions with detailed descriptions at discrete soil boring locations.

SUMMARY

The Norfolk District, U.S. Army Corps of Engineers was requested by Langley Air Force Base (LAFB) to prepare a preliminary geotechnical report. It is our understanding that information from the report will be used at a Planning Charrette scheduled for the end of October 2015. As part of Norfolk District’s Services to LAFB, the Geo-Environmental Section performed a limited subsurface exploration and prepared a preliminary geotechnical engineering report within the boundaries of the proposed project site as specified by LAFB personnel. The report provides a general characterization of the subsurface conditions at the project site, provides an overview of the soil conditions, and provides general guidance with respect to geotechnical engineering considerations. A limited environmental site assessment was performed as a part of this study.

The Contractor will be required to perform a geotechnical investigation to design and construct the appropriate foundation as part of their contract. This report is for information only and presents our understanding of the project, reviews the exploration procedures, and presents our observations, and provides general guidance with respect to geotechnical engineering considerations.

Due to man placed fill of variable consistency which overlies very loose to loose soils, and shallow water table conditions, it is our opinion that the proposed facility should be supported by means of a deep pile foundation system. Square precast pre-stressed concrete piles (SPPC) will be the most economical of the driven pile options and are one of the most widely utilized deep foundation systems in the Tidewater Area.

TABLE OF CONTENTS

1. PURPOSE

2. PROJECT INFORMATION

2.1 Scope of Work

2.2 Proposed Facility

2.3 Site Description

3. LIMITED SUBSURFACE EXPLORATION

3.1 General

3.2 Location

3.3 Soil Testing and Sampling

3.4 Laboratory Testing

4. SUBSURFACE CONDITIONS

4.1 Regional Geology

4.2 Subsurface Stratigraphy

4.3 Groundwater Conditions

5. PRELIMINARY GEOTECHNICAL ENGINEERING CONSIDERATIONS

5.1 Foundation Design

5.2 Ground Floor Slab-on-Grade

5.3 Seismic Site Classification for Design

5.4 Pavement Design Recommendations

5.5 Groundwater and Site Drainage

6. PRELIMINARY EARTHWORK CONSIDERATIONS

6.1 Site Preparation

6.2 Foundation Construction

6.3 Controlled Structural Fill

6.4 Suitability of On-site Material

6.5 Compaction Requirements

7. LIMITED ENVIRONMENTAL SITE ASSESSMENT CONCLUSIONS

AND RECOMMENDATIONS

7.1 Assessment

7.2 Conclusions

7.3 Recommendations

REFERENCES

Appendix A: Location and Geologic Maps Appendix B: Boring Location Plan, Boring Logs, and Profiles Appendix C: Laboratory Test Results Appendix D: Site Pictures

1. PURPOSE

This report has been prepared to provide a general characterization of the subsurface conditions at the project site and to provide a general overview of the soil and geologic conditions with detailed descriptions at discrete boring locations. It is furnished for information purposes.

The purpose of the report is to summarize the results of the subsurface exploration and laboratory testing undertaken by the Norfolk District, U.S. Army Corps of Engineers for a proposed Air Force Targeting Center Facility to be located at Langley Air Force Base (LAFB). The report is for information only and presents our understanding of the project, reviews the exploration procedures, and presents our observations, and provides general guidance with respect to geotechnical engineering considerations.

2. PROJECT INFORMATION

2.1 Scope of Work: The Norfolk District, U.S. Army Corps of Engineers was requested by Langley Air Force Base (LAFB) to prepare a preliminary geotechnical report. It is our understanding that information from the report will be used at a Planning Charrette scheduled for the end of October 2015. As part of Norfolk District’s Services to LAFB, the Geo-Environmental Section performed a limited subsurface exploration and prepared a preliminary geotechnical engineering report within the boundaries of the proposed project site as specified by LAFB personnel. A location map provided by LAFB personnel is attached in Appendix A.

The Norfolk District, U.S. Army Corps of Engineers (USACE) Geo-Environmental Section has also been requested by LAFB to provide information pertaining to the demolition of four (4) existing structures (Buildings 326, 333, 337, and 339) in association with the proposed project. A limited environmental assessment (ESA) was performed consisting of site reconnaissance, record search and interviews with base environmental and engineering offices.

2.2 Proposed Facility: According to documents provided by the Norfolk District Engineering Management Section, it is the understanding of the Norfolk District Geo- Environmental Section that the proposed Air Force Targeting Center Facility (AFTCF) is to be constructed as a two-story building and shall contain a total area of 94,800 square feet. The proposed facility must include space for 1,750 workstations and associated racks and communications equipment, mechanical space, conditioned computer warehouse space, and command staff offices for Center and three Squadrons. The facility space must accommodate crew size based on number, duration and frequency of worldwide targeting and geospatial intelligence operations in support of Allied Forces. The facility must also include space for operations, mission support, logistics support, and administrative support. It was also suggested that the facility include an emergency generator, site improvements, a foundation so that the building finished floor is ten (10) feet above mean high tide sea level, parking, and all necessary support. Due to the flooding in the Langley area, the building shall have finished floors above the appropriate design flood. Two intramural softball fields will also be demolished and relocated.

It is also our understanding that the project will also include the demolition of Buildings 326, 333, 337, and 339, which are located on the south side of the runway area. A location map is provided in Appendix A.

2.3 Site Description: The Air Force Targeting Center Facility will be constructed at Langley Air Force Base, Hampton, Virginia. The proposed building site lies southeast of the intersection of Helms Avenue and South Roma Road. Currently the site is a softball field, which is used for recreational purposes. Ground surface elevation was interpolated from USGS/FEMA LiDAR-2014 contour elevation maps provided by the Geospatial Section, Water Resources Division, Norfolk District USACE. A location map and project site contour elevation maps are provided in Appendix A.

3. LIMITED SUBSURFACE EXPLORATION

3.1 General: A limited subsurface exploration consisting of soil borings was performed to identify the subsurface material properties and define the subsurface stratigraphy. The subsurface exploration program consisted of soil borings with standard penetration tests (SPT). The soil borings tests were performed by Savannah District, U.S. Army Corps of Engineers under the supervision of an Engineer from Norfolk District, U.S. Army Corps of Engineers.

3.2 Location: A limited number of borings were evenly spaced across the site of the proposed facility. Boring locations were flagged in the field based on measurements from existing features. Latitude and Longitude coordinates for each boring location were interpolated on Google Earth Pro and converted to UTM Northing and Easting coordinates using the website http://www.latlong.net/lat-long-utm.html. Ground surface elevations for each boring were interpolated by USGS/FEMA LiDAR-2014 contour elevation maps provided by the Geospatial Section, Water Resources Division, Norfolk District USACE. The location and elevation are accurate only to the degree implied by this method used to their determination. Prior to drilling, all locations were cleared for underground utilities by Virginia Miss Utility, personnel from Safety and Quality Assurance Alliance (SQA2) at NASA Langley Research Center, and utility personnel at LAFB. Boring locations are shown on the enclosed subsurface exploration plan, provided in Appendix B.

3.3 Soil Testing and Sampling: Five (5) Standard Penetration Test (SPT) borings, designated as B-1 through B-5, were drilled at the proposed site. SPT boring:

B-5 was performed on 7 August and 8 August 2015 and drilled to an approximate depth of 70 feet below ground surface (bgs); B-2 was performed on 8 August and 9

August 2015 and drilled to an approximate depth of 94.3 feet bgs; B-4 was performed on 9 August and 10 August 2015 and drilled to an approximate depth of 75 feet bgs;

B-1 was performed on 10 August 2015 and drilled to an approximate depth of 35 feet bgs; and B-3 was performed on 11 August 2015 and drilled to an approximate depth of 35 feet bgs. SPT borings were performed in accordance with ASTM D 1586 with an All-Terrain mounted drill rig utilizing 3-inch roller cone open hole mud rotary procedures and 3 ¼-inch I.D. hollow stem auger procedures. Borings B-2, B-4, and B-5 were performed using the 3-inch roller cone open hole mud rotary procedures, and Borings B-1 and B-3 were performed using the 3 ¼-inch I.D. hollow stem auger procedures. Soil samples were obtained with a standard 2-inch outer diameter and 24-inch long split-spoon sampler driven with a 140-lb automatic hammer falling 30 inches. The number of blows required to drive the sampler for each six (6) inch penetration increment was recorded. The recovered soil samples were visually classified in the field in general accordance with ASTM D 2488. Portions of the recovered soil were placed in plastic storage bags, sealed, and tested for Volatile Organic Compounds (VOCs) using a MiniRAE 2000 portable VOC monitor, also known as a Photo-Ionization Detector (PID). The detector stores hundreds of Low, High, Time Weighted Average (TWA), and Short Term Exposure Limits (STEL) in its library. The preset limits vary and depend on which gas is detected by the device.

If VOC exposures exceed preset limits, an alarm will sound on the detector emitting three (3) beeps and flashes per second. The samples were then returned to the Norfolk District Office for review. Boring logs are included in Appendix B.

3.4 Laboratory Soil Testing: Laboratory soil testing was performed by Savannah

District, U.S. Army Corps of Engineers Materials Testing Regional Technical Center of Expertise, located in Marietta, Georgia. Twenty-two (22) soil samples, which were generally representative of the subsurface materials, were selected for classification tests (ASTM D 422, D 2216, D 2487, and D 4318). After the final laboratory testing report was submitted, it was brought to the attention of the Norfolk District Engineer that the project had been renamed. Although the laboratory test results were performed on the currently titled Air Force Targeting Center Facility project site, the results are designated with the previous project title, the 363 Intelligence, Surveillance, Reconnaissance, and Wing Facility (ISRWF). The laboratory test results were used to aid in soil classifications. Laboratory test results are provided in Appendix C.

4. SUBSURFACE CONDITIONS

4.1 Regional Geology: Langley Air Force Base is located approximately four (4) miles north-northwest of Hampton, Virginia and approximately 10 miles east of Newport News, Virginia. It is located in the Coastal Plain Physiographic Province.

Numerous transgressions and regressions of the Atlantic Ocean have deposited marine, lagoonal, and fluvial (stream lain) sediments. The regional geology is very complex, and generally consists of interbedded layers of varying mixtures of sands, silts, and clays. According to the Geologic Map of Virginia, the surficial soils belong to the Lynnhaven Member (Qtl) of the Tabb formation. These soils are described as pebbly and cobbly, fine to coarse gray sand grades upward into clayey and silty fine sand and sandy silt. Thickness varies from 0 to 20 feet (USGS). A copy of the geologic map of the site can be seen in Appendix A. These surficial deposits are underlain by the soils of the Yorktown formation. The Yorktown formation is Miocene in age. The top of the Yorktown formation typically consists of a relatively thin layer of bluish gray to gray highly plastic clay. The layer typically acts as an aquaclude between overlying soils and the underlying Yorktown soils. The underlying soils of the Yorktown formation typically consist of bluish gray to gray, fossiliferous, medium dense silty sands, and firm to very stiff sandy silts and silty sands. Shell beds are often abundant in this formation. The Yorktown stratum, once encountered, generally extends to depths in excess to 150 feet below sea level.

4.2 Subsurface Stratigraphy: The subsurface conditions discussed in the following section and those shown on the boring test logs represent interpretations of the boring data and are for information only. The lines designating strata breaks on the boring logs and those indicated below represent approximate boundaries between soil types, as the transition may be gradual or may occur between samples. The generalized subsurface stratigraphy is our interpretation of the soil stratigraphy and subsurface condition at the project site based on our subsurface exploration and available information. The interpretation necessarily assumes uniform subsurface conditions across the site, which is probably, but not necessarily, correct. The general descriptions, below, should not be considered as a substitute for the boring logs.

Generalized subsurface profiles for the site are also included in Appendix B of this report.

A surficial soil layer was encountered to a depth of approximately 4-inches bgs in the soil borings. This soil is typically a Very Loose to Loose, Brown Silty Fine SAND with organics and roots. Roots (organic matter) were encountered in all borings to a depth of 4.0-inches to 4.0 feet bgs. Boring B-5 contained trace roots extending from depths 4.0 to 6.0 feet bgs.

For Borings B-1 through B-4, underlying the surficial soils is a layer of man placed fill material which consists of Loose to Medium Dense, Brown, Yellowish Brown, Reddish Brown, Orangish Brown, Tan and Black, Fine to Coarse, Silty SAND, with pea gravel, gravel and roots, classified as SM. Boring B-2 encountered a hard object at its original drilling location approximately 5.0 feet bgs. The drill rig moved east

3.0 feet and encountered a hard object at approximately 2.5 feet bgs. The drill rig moved east an additional 3.0 feet (6.0 feet total offset) and encountered another hard object at approximately 2.5 feet bgs. The 3-inch roller cone was removed and a hollow stem auger was installed to drill through the hard material. The hollow stem auger penetrated through the hard material to approximately 4.0 feet bgs, where the 3-inch roller cone was re-installed and the next split-spoon sample was collected.

Based on auger cuttings and debris encountered in the split spoon samples, it was determined that the hard material encountered was red brick and gravel. Refer to Photo 1 in Appendix D. Red brick and a cobble rock measuring approximately 4-inches in diameter was also encountered at Boring B-4 while advancing the hollow stem auger through hard material ranging in approximate depth of 2.0 to 4.0 feet bgs.

This is shown in Photo 2 in Appendix D. The fill material for Borings B-1 through B-4 was encountered to an approximate depth between 2.0 to 5.3 feet bgs. Boring B- 5 contained possible fill material which consists of Loose, Brown, Yellowish Brown, Orangish Brown and Gray Silty and Clayey Fine to Medium SAND with trace pea gravel and roots, classified as SM or SC. This material was encountered to an approximate depth of 6.0 feet bgs. SPT N-values for Borings B-1 through B-4 ranged from 9 to 19 blows per foot (bpf) with an average of 14.1 bpf. SPT N-values for Boring B-5 ranged from 7 to 10 blows per foot (bpf) with an average of 8.5 bpf.

Refer to Table 1 below for the approximate depths of fill and possible fill for each boring.

According to the laboratory soil tests on selected samples, the moisture content for the fill and possible fill material ranged from 8.2 to 19.9 percent with an average of

14.1 percent. The percent passing the No. 200 Sieve ranged from 30.1 to 36.7 percent with an average of 33.4 percent.

PID readings recorded for the fill material appeared to range consistently in value.

The readings for the fill material were encountered to range in value of 1.5 to 9.3 parts per million (ppm) with an average of 5.7 ppm. The PID meter did not detect VOCs for Boring B-5 from depths 0 to 38 feet bgs possibly due to the poor sealing capability of the plastic storage bags used to store the samples. At depth 38 feet bgs different storage bags were used to store the samples and the PID meter was capable of detecting VOCs for the samples through termination of boring. The PID meter did not exceed preset levels of VOCs, which would have allowed the detector to beep, flash, or set off an alarm. No odors were detected for the fill and possible fill material. PID readings are shown in Table 1 below.

Table 1. Fill Material and Possible Fill Material Depths and PID Readings

Boring Approximate Depth Range bgs

(feet)

PID

(ppm) B-1 (fill material) 0.3 - 2.0 6.0 B-2 (fill material) 0.3 - 5.0, possibly deeper 1.5 to 7.1 B-3 (fill material) 0.3 - 5.3 2.0 to 9.3 B-4 (fill material) 0.3 - 4.0 5.4 to 8.7

B-5 (possible fill material) 0.3 - 6.0 No Reading

Underlying the layer of fill and possible fill materials, is a layer which consists of Very Loose to Loose, Brown, Orangish Brown, Yellowish Brown, Reddish Brown, Tan and Black, Fine to Coarse Silty and Clayey SAND, classified as SM or SC. This material was encountered to an approximate depth of 9.8 to 12.0 feet bgs. Shell fragments were encountered in Borings B-2 and B-3, ranging in depths from approximately 8.0 to 12.0 feet bgs. Little pea gravel was encountered in Boring B-4 ranging in depth from approximately 4.0 to 6.0 feet bgs. SPT N-values ranged from 0 to 13 bpf with an average of 4.6 bpf. This material has been designated as Stratum I for this site.

According to the laboratory soil tests on selected samples, the moisture content for the Stratum I ranged from 20.5 to 36.5 percent with an average of 25.6 percent. The percent passing the No. 200 Sieve ranged from 14.4 to 39.5 percent with an average of 24.5 percent.

PID readings recorded for Stratum I consistently decreased with depth. The readings for Stratum I were encountered to range in value of 3.2 to 9.3 parts per million (ppm) with an average of 5.2 ppm. The PID meter did not exceed preset levels of VOCs, which would have allowed the detector to beep, flash, or set off an alarm. No odors were detected for Stratum I. PID readings are shown in Table 2 below.

Table 2. Stratum I Depths and PID Readings

Boring Approximate Depth Range bgs (feet)

PID

(ppm) B-1 2.0 - 12.0 2.5 to 9.3 B-2 5.0 - 12.0 3.2 to 4.3 B-3 5.3 - 12.0 3.7 to 8.2 B-4 4.0 - 12.0 4.4 to 7.6 B-5 6.0 - 9.8 No Reading

Underlying Stratum I was a Very Loose to Very Dense, Gray and Bluish Gray, Silty and Clayey Fine SAND with varying sizes and amounts of shell fragments, classified as SM or SC. This material was encountered to the depth of termination for all borings. Boring B-2 contained a layer of Stiff to Very Stiff, Gray and Bluish Gray CLAY with some silt and shell fragments, classified as CL, ranging in depth from approximately 68.0 to 72.0 feet bgs. SPT N-values ranged from 1 to 50+ bpf with an average of 8.6 bpf. This material has been designated as Stratum II for this site.

The moisture content for the Stratum II ranged from 23.2 to 38.0 percent with an average of 33.5 percent. The percent passing the No. 200 Sieve range from 14.7 to

55.5 percent with an average of 23.9 percent.

PID readings recorded for Stratum II varied with depth and were found to be inconsistent for all borings. The readings for Stratum II were encountered to range in value of 0.8 to 25.4 parts per million (ppm) with an average of 5.4 ppm. In Boring B- 2 PID readings were encountered to range in value of 17.1 to 25.4 ppm, at the approximate depths of 23 to 25 feet and 38 to 50 feet bgs. The PID meter did not exceed preset levels of VOCs, which would have allowed the detector to beep, flash, or set off an alarm. Naturally occurring chemical compounds and hot, sunny, and humid weather conditions may be a possible cause for the higher VOC levels detected in Boring B-2. No odors were detected for Stratum II. PID readings are shown in Table 3 on the following page.

Table 3. Stratum II Depths and PID Readings

Boring Approximate Depth Range bgs (feet)

PID

(ppm) B-1 12.0 - 35.0 0.9 to 2.8 B-2 12.0 - 94.3 1.2 to 25.4 B-3 12.0 - 35.0 2.8 to 9.2 B-4 12.0 - 75.0 0.8 to 9.3 B-5 9.8 - 70.0 **1.3 to 10.1

**Beginning at 38 feet bgs.

4.3 Groundwater Conditions: Groundwater was measured at each borehole approximately after auger removal and 24 hours after drilling operations. The water level was observed to range approximately 5.0 to 6.8 feet bgs approximately 24 hours after drilling operations were complete. A temporary well was also installed approximately 6.0 feet south of Boring B-4 on 9 August 2015. It was installed to a depth of approximately 10.0 feet bgs with approximately 5.0 feet of screen and 5.0 feet of riser. The water level was observed at approximately 6.5 and 7.0 feet approximately 24 hours after installation and 48 hours after installation.

The depth to groundwater that was observed at time of the exploration does not reasonably represent the conditions that will be encountered during construction or for the life of the building. Due to the shallow water table conditions encountered in the borings, groundwater could be found close to the ground surface. Groundwater levels are expected to fluctuate with seasonal changes, periods of heavy or little rainfall, tides, pumping from wells, and other factors. The near surface soils can become soft and wet.

5. PRELIMINARY GEOTECHNICAL ENGINEERING

CONSIDERATIONS

5.1 Foundation Design: Based on the results of the preliminary subsurface exploration program, it is our opinion that the proposed facility should be supported by means of a deep pile foundation system. Square precast pre-stressed concrete piles (SPPC) will be the most economical of the driven pile options and are one of the most widely utilized deep foundation systems in the Tidewater Area. The piles are available in sizes from 10 to 24 square inches, and are typically designed for allowable pile loads of between 35 to 250 tons (70 to 500 kips). Lengths of piles typically in the Tidewater Area may vary between 40 to 80 feet to obtain the required capacity.

Table 4 on the following page provides our preliminary estimates of pile capacities for various SPPC dimensions and tip elevations for the facility’s foundation system while using a factor of safety of 3. These values are not for design but for general planning. The design needs to consider other factors but not limited to building loads, site grading, and horizontal deflections. The Contractor will need to perform an analysis to determine the actual pile capacity and settlements. Verification load testing shall be included as part of the contract for production piles during construction. The capacity of a group of piles should not be spaced less than three (3) pile diameters apart, center to center, and a reduction of capacity will be needed for pile groups. The final order lengths and tip elevations will be adjusted based on the results of the test piles and load test programs.

Table 4. Square Precast Pre-stressed Concrete Pile Sizes and Approximate Capacities

SPPC

Dimensions

(ft)

Embedment Depth

(ft)

Approximate Allowable

Compression Capacity (kips)

Approximate Allowable

Tension Capacity (kips)

12-in x 12-in

90 45 16-in x 16-in 150 70 18-in x 18-in 200 85 12-in x 12-in

95 50

16-in x 16-in 160 75 18-in x 18-in 215 95 12-in x 12-in

100 55

16-in x 16-in 170 85 18-in x 18-in 225 105 12-in x 12-in

110 60

16-in x 16-in 180 90 18-in x 18-in 240 115 12-in x 12-in

115 65

16-in x 16-in 190 100 18-in x 18-in 255 125

The piles are expected to derive the majority of their capacity from shaft friction with minor end bearing in sand layers at deeper depths. The soil materials typically exhibit time-dependent strength characteristics. The dynamics of driving piles will cause excess pore pressures to develop, thereby decreasing driving resistance during initial pile installation. Once driving is complete, the excess pore pressures dissipate with time and the bearing capacity of the pile increases. Several days will be required for the excess pore pressures to dissipate. Due to these reasons, it will not be possible to confirm pile capacities with a simple driving criterion such as number of hammer blows per foot or advanced pile. Instead, driving criteria will likely consist of a target tip elevation and/or certain embedded length in a bearing material with specified driving resistance. The specified driving resistance should be based on a Wave Equation Analysis of the Contractor’s selected hammer. Pre-drilling may also be required to certain depths below the ground surface to aid in the installation of the piles through existing fill and debris, and to reduce the potential of breakage.

The proposed facility finished floor shall be constructed above the appropriate design floor. Several feet of controlled structural fill, selected by the Contractor, shall be necessary to raise the final floor of the facility above future flood elevation. Refer to section 6.3 for controlled structural fill recommendations.

5.2 Ground Floor Slab-on-Grade: The ground floor slabs-on-grade for the proposed building may be supported on properly compacted controlled structural fill resting above the in-situ fill soils. The existing man-placed fill can remain in place if the ground floor slab is lightly loaded with general office furniture. Some undercutting and replacement of existing fill soils may be required if soils are soft or unsuitable as identified during the proof-rolling procedure of the subgrade. If the slab will be heavily loaded with large equipment, then the slab shall be structurally supported on the deep foundation system.

A four-inch thick granular base layer consisting of open-graded crushed stone (VDOT 57 crushed stone) or clean sand (ASTM C-33 Sand) should be placed beneath the floor slabs. This granular base would function as a leveling and load disturbing material for the slab and provide a capillary break beneath the slab.

A vapor barrier should be used beneath ground floor slabs that will be covered by tile, wood, carpet, impermeable floor coatings, and/or if other moisture-sensitive equipment or materials will be in contact with the floor. Utility and other excavations within the subgrade of the floor slabs shall be backfilled with properly compacted structural fill in accordance with the project specifications to provide uniform floor slab support.

5.3 Seismic Site Classification for Design: The site soils were classified in accordance with ASCE Standard ASCE 7-05, Chapter 20 based on the Standard Penetration Resistance (N) obtained from the 94.3 foot boring. The average N values over the upper 100 feet of soil was determined to be less than 15 bpf, and in accordance with this method the site class is defined as Site Class E. The most accurate site classification can be obtained by using the average shear wave velocity procedure; however, this requires special testing such as surface wave tests or seismic cross-hole tests. Performing such tests may lead to a more favorable site classification which will lead to lower design forces and possible savings in the building structure.

5.4 Pavement Design Recommendations: The following general pavement recommendations are made: design adequate grading to provide runoff away from paved surfaces and beyond the limits of paved area and building areas. We recommend underdrains at low points in the pavement to limit water penetration into the base course and subbase.

The ability of the existing subgrade soils to support pavement structures may be variable across the site. The existing subgrade soils are moisture sensitive and will lose stability when subjected to moisture and construction traffic. It is recommended that pavement construction be performed during the summer months and to provide positive drainage to prevent moisture from ponding on the subgrade.

5.5 Groundwater and Site Drainage: Groundwater was encountered in all borings at a relatively shallow depth. Approximately 24 hours after drilling the water level in the borings ranged from 5.0 to 7.0 feet below the surface. Based on our observations the relatively shallow groundwater will probably impact excavations performed on this site. Dewatering such as sumps with pumps or wells will be required for most utility excavations. Temporary drainage ditches should also be employed by the Contractor to accentuate drainage during construction.

6. PRELIMINARY EARTHWORK CONSIDERATIONS

6.1 Site Preparation: Proper site preparation will be critical to this project in order to achieve satisfactory performance of the structure. It is recommended that a Geotechnical Engineer be retained to provide soil engineering services during the actual site preparation and foundation construction phase of the project to perform appropriate evaluations to help assure that conditions encountered during construction are similar to the conditions encountered in the subsurface exploration. The Geotechnical Engineer can also assist in interpretation of differing subsurface conditions that may be encountered and recommend remedial work, if needed.

Site preparation for the building pad and pavements should include complete removal of surface vegetation, surficial soils, organic material, trees, tree stumps, roots and organic soils. Measured topsoil in the borings was generally four (4) inches thick.

However, some roots were encountered in borings extending 2.0 to 6.0 feet below the surface. Topsoil is defined as the upper surface soils that contain roots and other organic material. Due to groundwater conditions encountered on the site, the removal of the existing fill would be an expensive undertaking.

Stripping of topsoil should be performed to a horizontal distance of at least 10 feet beyond the limits of the building footprints, and five (5) feet beyond the limits of pavement in the undeveloped areas. Areas of construction should also be cleared of soft, wet, or disturbed soils. Over-excavated areas should be backfilled with properly compacted suitable fill. During the clearing and stripping operations, positive surface drainage should be maintained to prevent the accumulation of water.

After stripping, the exposed subgrade soils in the areas of development should be proof-rolled with a 15-ton loaded dump truck or other pneumatic-tired vehicle of similar size and weight. Proof-rolling should be observed by a Geotechnical Engineer and the Contracting Officer. Proof-rolling should be performed during a period of favorable weather and not while the site is wet, frozen, above planned grade, or severely desiccated. Any unsuitable materials that are observed to yield or rut noticeably during proof-rolling should be under and replaced with compacted imported controlled structural fill or stabilized in-place as recommended by the Geotechnical Engineer and approved by the Contracting Officer.

The near surface subgrade soils are moisture sensitive and will lose stability if these soils become wet and are subjected to construction traffic. As a result, site preparation should be performed during an extended period of dry weather.

Undercutting or reworking by aerating or discing or the near surface soils may be necessary if the exposed subgrade soils become unstable during construction. Any fill materials, aggregates, and/or concrete should be placed as soon as possible over the approved subgrade in order to reduce exposure of the subgrade to weather and construction activity. It is important to stress that the subgrade needs to be properly prepared and protected during construction to minimize the degradation of these soils.

6.2 Foundation Construction: Test piles should be driven at the site within the proposed foundation areas prior to installation of production piles. The purpose of the test piles is to attempt to verify bearing depths, axial compressive capacities, and driving conditions across the site. Test piles should be 10 feet longer than the anticipated pile design length and should be driven to the indicated design bearing depth. The Geotechnical Engineer of record should witness the test pile installation.

The test piles should be located to provide coverage over the planned foundation areas. The number of test piles will be dependent upon the combination of the pile types and bearing elevations selected for the project. Test piles may be installed at planned permanent pile locations and utilized if adequate capacity is achieved. The test pile locations should be reviewed and approved by the Geotechnical Engineer of record. As a minimum, two static load tests per ASTM D 1143 shall be performed for the building. Pile re-strikes shall be performed in accordance with ASTM D 4945. A dynamic pile analysis shall be performed on each pile. The pile re-strikes shall not be performed until at least 3-days after test pile installation. The pile hammer used in the test pile program shall have sufficient energy to “prove” at least 250% of the specified allowable pile design capacity(ies). Application of the test load should be performed under the direction of a Geotechnical Engineer.

A wave equation and drivability evaluation should be performed for the proposed pile hammer assembly prior to the start of the test pile program. CAPWAP analyses should be performed on the PDA measurements obtained from the test piles indicated. Depending on the findings of the dynamic testing, the specified pile load test may be deleted at the discretion of the Geotechnical Engineer of record. In addition, some adjustment of the design capacities or bearing depths may be necessary.

6.3 Controlled Structural Fill: Fill placed beneath buildings, structures, and under roadways which will raise the site to the finished subgrade shall be compacted structural fill. Controlled structural fill material under buildings and the roadways should be non-expansive and free of organic matter, debris, and particles larger than two (2) inches in size. Proposed fill materials should be subjected to laboratory tests consisting of, but not necessarily limited to, moisture density determinations, Atterberg limits, and sieve analysis. Controlled Structural Fill under buildings, pavements, and structures should classify per USCS as SW, SP, SP-SM, SM, or SC with a maximum of 35 percent fines passing the No. 200 sieve.

6.4 Suitability of On-site Material: Due to existing fill, groundwater elevations, and debris encountered in the borings on the site, it is our opinion that structural fill will need to be imported from off-site. The imported fill shall conform to the recommendations above. The on-site soils will not be suitable for reuse as backfill in excavated utility trenches. Backfill material in utility trenches within the construction areas should consist of structural fill (as described in the previous section), and should be compacted to at least 95 percent of the standard Proctor maximum dry density in accordance with ASTM D 698. This fill should be placed in 4 to 6 inch loose lifts when hand compaction equipment is used.

6.5 Compaction Requirements: The contractor shall provide proper equipment to meet compaction requirements based on a modified Proctor (ASTM D 1557). Due to the higher energy from the modified Proctor, the optimum moisture content of the material will be lower than a standard Proctor. The in-situ moisture content of the subsurface material is expected to be higher than the optimum moisture content from a modified Proctor. The contractor should be prepared to adequately dry the in-situ soils prior to placement as backfill. The compaction requirements for this project are listed below:

Structures, Foundations, and Concrete Slabs: Compact top 12 inches of subgrade and subsequent structural fill to 95 percent of ASTM D 1557.

Roads and parking areas: Compact top 12 inches of subgrade and subsequent fill to 95 percent of ASTM D 1557.

Green Areas: Compact to 85 percent of ASTM 1557.

Maximum loose lift thickness shall be eight (8) inches and 12 inches under buildings and pavements, respectively. Proper compaction equipment should be utilized by the contractor to achieve the required compaction. For areas which do not permit the use of heavy compaction equipment (utility trenches) lift thickness shall be reduced to six

(6) inch loose lifts to achieve the required compaction. During fill operations, positive surface drainage should be maintained to prevent the accumulation of water.

Each lift of fill should be tested in order to confirm that the degree of compaction is attained. Field density tests to verify fill compaction should be as required by the earthwork specification.

The moisture of backfill material should be maintained within three (3) percentage points of the optimum moisture content as determined from the modified Proctor.

Compaction requirements may be reduced by five (5) percent for cohesive material, defined as material contained more than 50 percent fines (material passing the No.

200 sieve).

Care should be used when operating the compactors near existing structures to avoid transmission of the vibrations that could cause settlement damage or disturb occupants. In this regard, it is recommended that the vibratory roller remain at least 25 feet away from existing structures; these areas should be compacted with small, hand-operated compaction equipment.

7. LIMITED ENVIRONMENTAL SITE ASSESSMENT

CONCLUSIONS AND RECOMMENDATIONS

7.1 Assessment: Discussions with the 633 Civil Engineer Squadron, Environmental Element personnel and records review provided copies of Hazardous Material Inspections that were performed on the four (4) buildings slated for demolition.

During the time spanning April 1991 through July 1991, Asbestos surveys were performed on all four (4) buildings. The surveys provided visual inspection and destructive sampling of suspected Asbestos Containing Materials (ACM). The resulting reports provided percent concentrations of asbestos and locations, along with projected costs for removal. It is believed that these surveys were performed prior to a planned renovation and it is apparent that this and/or additional renovations have occurred to the buildings since 1991. These reports did not provide any information about other potential hazardous materials (mercury or PCB containing components and lead paint). An additional Asbestos Inspection and Hazardous Material Inspection was performed at Building 326 in May 2011. This work was performed in preparation for renovations specifically associated with rooms 104, 106, 108, and 112 and was not performed on the entire building. Environmental research for the Air Force Targeting Facility site was also performed during the assessment, but no historical information could be found.

7.2 Conclusions: The asbestos assessments performed in 1991 positively identified the presence of ACM in buildings 326, 333, 337, and 339. Additionally, the limited Asbestos Inspection of Building 326 performed in 2011, also confirmed the presence of ACM in rooms 104, 106, 108, and 112. Further inquiries to the engineering department at LAFB revealed that removal of ACM from the four (4) buildings could not be confirmed from existing records. The continued presence of ACM in Building 326 in May 2011 supports the conclusion that ACM is likely remaining in all the building slated for demolition.

The limited 2011 Hazardous Materials Inspection performed at building 326 in 2011, concluded mercury containing fluorescent bulbs and potentially PCB containing light ballasts is present. No information on the presence of lead based paint was discovered during the document review.

7.3 Recommendations: The LAFB should procure a comprehensive HAZMAT Survey and provide these results (as well as previous assessments) to the Contractor.

The Contractor should be directed that all ACM and hazardous materials be removed and disposed of in accordance with applicable law prior to demolition of the buildings.

Hard copies of historic assessments reside in-house and at the Langley 633 Civil

Engineer Squadron, Environmental Element.

REFERENCES

Google. Map of Langley Air Force Base, Hampton, Virginia.

<https://www.google.com/maps/@?hl=en >

USACE. GIS Map of Virginia. < http://nao-ap-oracle.nad.ds.usace.army.mil:7777/pls/apex/f?p=106:1:622262098569401:::::>

USGS. “Tabb Formation, Lynnhaven Member.”

<http://mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=VAQtl%3B0>

APPENDIX A:

LOCATION AND GEOLOGIC MAPS

A1

Map 2. Langley Air Force Base, Hampton Virginia. Red circle indicates project site (Google).

Map 3. Air Force Targeting Center Facility project site. Red circle indicates location (Google).

A2

Sweeney Blvd Sweeney Blvd

Lee R d.

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R d.

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Nealy Ave

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Weyland Rd

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Poplar Rd.

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Dan fo rth Ave

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Be ne di ct

Ave

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Ave

Durand St.Durand St.

H olly S t H olly S t

Gray Ave Gray Ave

Glover Ave

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Plumb St

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Th or ne ll

Av e

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Av e

Em mons

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Douglas St.

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Spaatz Dr.

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Bowen St.

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P ine R d.

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Helms AveHelms Ave

Dur an d Rd

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Dogwood Ave Dogwood Ave

Harris Ave Harris Ave

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Walnut Ave.

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O ak R d.

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Cedar Ave Cedar Ave

Hamm ond Ave

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Andrews St

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Durand Loop Rd

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Ash Ave Ash Ave

A lert D r.

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H ickory R d.

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Sm yth e Rd.

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Bryant Ave

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Beech Ave.

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S pruce S t S pruce S t

Butternut Ave Butternut Ave

M agnolia S t.

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Basswood Ave Basswood Ave

Sperry C t

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Lee Rd Lee Rd

W right Ave

W right Ave

Wrig ht Ave

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Dogwood Ave Dogwood Ave

Sweeney B lvd

Sweeney B lvd

King S t King

S t

Elm St

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Although every effort has been made to ensure the accuracy of information, errors and conditions originating from physical sources used to develop the database maybe reflected in the data supplied. The end user must be aware of the data conditions and ultimately bear responsibility and the appropriate use of the information with respect to possible errors, original map scale, collection methodology, currency of data, and other conditions specific to certain data.

LIMITED DISTRIBUTION

Distribution authorized to DoD, IAW 10 U.S.C. §130 & 455. Release authorized to U.S. DoDcontractors IAW 48 C.F.R.

§252.245-7000.

Removal of this caveat is prohibited.

This material is For Official Use Only.

Unauthorized reproduction, distribution, publication, or exhibition of this material is STRICTLY PROHIBITED. Refer other requests to 1CES/CEG. Destroy as "For Official Use Only". 1CES/CEG shall not be liable for any errors, omissions, or damages that result from noncompliance of this message.

Langley AFB, VA

Coordinate System:

NAD 83 Virginia State Plane South Zone 4502

Vertical Datum:

NAVD 88

Data Provided By:

1FW Geo Integration Office

Mapping Consultant Geobase Project ID Print Date

BASE MAP

SRA SOTO

CUSTOM

02AUG05

0 2,500 5,0001,250 Feet

A3

E4TSEJLS

Oval

E4TSEJLS

Oval

E4TSEJLS

Oval

E4TSEJLS

Text Box Map 3. The blue circles indicate the buildings to be demolished as a part of the project (Buildings 326, 333, 337, and 339).

US Army Corps of Engineers Norfolk District

Map: Targeting_Facility_Contours Developed By: Jason O'Neal Date: 10/16/2015I

1 in = 100 feetAir Force Targeting Center Facility Langley Air Force Base

Hampton, Va

Elevation Data Source:

USGS/FEMA LiDAR - 2014 Coordinate System:

NAD_1983_HARN_StatePlane_Virginia_South

0 10050 Feet

US Army Corps of Engineers Norfolk District

Map: Targeting_Facility_Contours Developed By: Jason O'Neal Date: 10/16/2015I

NAVD88 (feet) High : 23

Low : 4

1 in = 100 feetAir Force Targeting Center Facility Langley Air Force Base

Hampton, Va

Elevation Data Source:

USGS/FEMA LiDAR - 2014 Coordinate System:

NAD_1983_HARN_StatePlane_Virginia_South

0 10050 Feet

Map 7. Surficial soils located near LAFB, Hampton, Virginia. Red circle indicates LAFB

(USACE).

Map 8. Surficial soils at Air Force Targeting Center site belong to the Lynnhaven Member (Qtl).

Red circle indicates project site location (USACE).

APPENDIX B:

BORING LOCATION PLAN, BORING LOGS,

AND PROFILES

AIR FORCE TARGETING CENTER

LANGLEY AIR FORCE BASE, HAMPTON, VIRGINIA

BORING LOCATION PLAN

B‐4

B‐5

B‐2

B‐1

B‐3

Google 2015

0.3 0.5

2.0

3.0

4.0

6.0

12.0

27.0

[TOPSOIL] Very Loose, Brown and Yellowish Brown, Silty Fine to Coarse SAND with organics and roots, (4 inches) [FILL] Medium Dense, Brown, Black, Yellowish Brown and Orangish Brown, Silty Fine SAND, with small pea gravel, moist [FILL] Medium Dense, Orangish Brown and Black, Silty Fine to Coarse SAND with pea gravel, moist, roots [SM] Loose, Brown and Tan Silty Fine to Coarse SAND with some clay and roots, moist [SC] Loose, Brown and Orangish Brown Clayey Fine to Coarse SAND, moist [SC] Loose, Brown Mottled Gray and Orangish Brown Clayey Fine to…