09R0036-SPECS-VOL2.PDF

RFP W912BU-09-R-0036

US Army Corps of Engineers

Philadelphia District

Design-Build Skills Development Center and Car Wash

Dover Air Force Base, Delaware

Volume 2 of 2

Design Criteria and Specifications

19 June 2009

This page was intentionally left blank for duplex printing.

Table Of Contents – Page 1

PROJECT TABLE OF CONTENTS

DESIGN BUILD

SKILLS DEVELOPMENT CENTER AND CAR WASH

DOVER AIR FORCE BASE, DELAWARE

Volume 1 of 2

DIVISION 01 - General Requirements

01 10 00 Statement of Work 01 14 00 Work Restrictions 01 32 01 Project Schedule 01 32 33 Construction Photography 01 33 00 Submittal Procedures 01 33 16 Design After Award 01 35 26 Governmental Safety Requirements 01 35 40 Hazardous Materials Usage 01 45 01 Quality Control System (QCS) 01 45 04 Contractor Quality Control 01 50 02 Temporary Construction Facilities 01 57 20 Environmental Protection 01 62 00 Affirmative Procurement 01 62 35 Recycled or Recovered Materials 01 74 19 Construction and Demolition Waste Management 01 78 02 Closeout Submittals 01 80 00 Commissioning

Volume 2 of 2

Appendix A Geotechnical Report and Requirements Appendix B Geophysical Investigation Drawings and Report Appendix C Preliminary Hydraulic Sprinkler Calculations and Water Flow Test Appendix D Storm Water Management Waiver Report Appendix E LEED Design Checklist Appendix F Equipment List Appendix G Environmental Investigation Report Appendix H Dover Air Force Base Architectural Compatibility Plan Appendix I Dover Air Force Base Local MILCON and RPMC Design Guide

Appendix A

Geotechnical Report and Requirements

APPENDIX A Page 1

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APPENDIX A – GEOTECHNICAL REPORT AND REQUIREMENTS

SKILLS DEVELOPMENT CENTER (SDC) - DOVER, DELAWARE

1. SUBSURFACE SOIL CONDITIONS

The soil conditions encountered during subsurface exploration conducted at the site generally consisted of two strata; in order of increasing depth below the pavement or ground surface, the soil strata included a surface cover of asphalt or topsoil overlying a 2-4 foot thick fill stratum underlain by naturally deposited alluvial soils. The fill stratum typically consisted of sandy lean clay, silt, and clayey/silty sand (CL, CL-CL-ML, ML, SM, and SC). The alluvial soil strata consisted of intermittent cohesive and granular alluvial deposits. The cohesive alluvial soils ranged from stiff to very stiff yellow-brown and red-brown silt and clay (CL, CL-ML, and MH). The granular alluvial soils ranged from loose to very dense dark brown and orange brown clayey, silty, well graded and poorly graded sand (SC, SM, SW-SM, SP-SC, SP-SM, and SP). The groundwater table is located between 15.4 and 16.1 feet below the ground surface, corresponding to elevations of 6.6 and 7.1, respectively.

Actual soil and ground water conditions between boring locations may differ from these typical descriptions. Refer to the test boring logs for specific descriptions of soil samples obtained from the borings.

2. SUBGRADE PREPARATION

Any surface cover consisting of topsoil, or previously placed asphalt or base course shall be removed, in addition to any existing underground structures or associated structural debris encountered during grading operations. If foundation recommendation Alternative 2: Short-aggregate Piers is not exercised then on-site fill soil shall be over-excavated to a minimum depth of 4 feet and replaced with structural fill. After sufficient removal of the cover and fill material the subgrade shall be proof rolled. Areas exhibiting excessive pumping, weaving, or rutting shall be excavated and replaced with additional compacted structural fill. Ground surfaces that are muddy, frozen or contain frost shall not be backfilled over. Compacted structural fill shall be used to bring the subgrade elevation up to the final design grade.

3. STRUCTURAL FILL

The structural fill used to backfill the building foundation area shall extend a minimum of 5 feet horizontally outside the building limits, and shall consist of materials classifying as GW, GP, GM, SW, SP, or SM. The liquid limit and plastic index must not exceed 35 and 12 percent, respectively, when tested in accordance with ASTM D 2434. The structural fill shall be placed and compacted in accordance with the specified compaction requirements.

4. COMPACTION REQUIREMENTS

Structural fill shall be placed and compacted in horizontal layers not exceeding a 6 inch loose lift thickness. Each lift shall be compacted to 95 percent of maximum dry density in accordance with ASTM D1557, Modified Proctor, and to within 2 percent of optimum moisture using pneumatic-tired rollers, steel-wheeled rollers, or other approved equipment suited for the soil material being compacted.

APPENDIX A Page 2

5. FOUNDATION RECOMMENDATIONS

There are two foundation alternatives recommended for the Skills Development Center and Car Wash. The first involves over excavation and replacement of the upper fill stratum; whereas, the second involves the use of short-aggregate piers as a means of ground improvement and stabilization.

a. Alternative 1: Over-excavation

The natural alluvial stratum underlying the fill material is capable of supporting spread foundations for the proposed structure. The fill material should be over-excavated to a minimum depth of 4 feet and replaced with compacted structural fill. The excavated material may be stockpile and re-used as fill material in non-structural and non-paved areas.

Shallow spread footings bearing on the natural alluvial soils or on approved compacted structural fill material are suitable to support the proposed structures. The footings should be designed to support a net allowable soil bearing pressure of 3,000 pounds per square foot (psf). The interior footings may be installed at a nominal depth below the structure’s floor slab as determined by the design engineers. The exterior footings should be installed at a minimum depth of 2.5 feet below the ground surface to account for frost-heave considerations.

b. Alternative 2: Short-aggregate Piers

Short-aggregate piers such as Geopiers™, impact piers or vibro-replacement stone columns are recommended to (1) limit and minimize the amount of overexcavation and subgrade improvement,

(2) minimize the potential for differential settlement under the footings, and (3) stiffen and improve the subgrade conditions, resulting in higher allowable bearing pressures.

Short-aggregate piers are formed by creating a cavity within the matrix soil by auguring or vibrating open holes and densely compacting the aggregate within the cavity in thin lifts. Geopiers™, impact piers and vibro-replacement stone columns produce similar short aggregate piers using different installation methods.

For Geopiers™, the matrix soil at the bottom of the cavity and the aggregate lifts are compacted using a special high energy, relatively high frequency impact tamper. During these compaction processes, the soil at the bottom of cavity is prestrained and prestressed, and the aggregate displaces the matrix soil outward, resulting in a buildup of horizontal confining pressures, much higher soil modulus than the original soil, and reducing vertical displacements prior to structural loading. The final product is very dense short pier element with an irregular perimeter surface. The height of an aggregate pier is generally between three to four times its diameter or width. The piers are normally not extended to stronger, deeper zones. The installation of Geopiers™ produces spoils that need to be considered on sites with restricted area or environmentally sensitive areas.

An impact pier is a vertical displacement rammed aggregate pier used to reinforce good to poor soils, including loose sands, and soft silts and clays, uncontrolled fill soils and soils that cave upon drilling or are below the ground water table. The installation process uses vertical impact ramming energy to displace the soil laterally along the full design depth by pushing a specially designed mandrel and tamper foot using a relatively large static force augmented by dynamic impact energy.

The lateral displacement of the soils thus eliminates spoils. A sacrificial cap prevents soil from entering the tamper foot and mandrel. After driving to design depth, the hollow mandrel serves as a conduit for the placement of aggregate. The aggregate is placed inside the mandrel and the mandrel is lifted, leaving the sacrificial cap at the bottom of the pier. The tamper foot is lifted

APPENDIX A Page 3 approximately three feet and then driven back down two feet, forming a one-foot thick compacted aggregate lift. This compaction process continues upward along the length of the shaft to the ground surface.

Vibro-replacement stone columns are formed using a vibratory probe that penetrates the ground under its own weight or in some cases with water jetting. Stone is fed into the bottom of the cavity and densified using vibration. Similar to Geopiers™, the walls of cavity are prestrained and prestressed, and the aggregate displaces the matrix soil outward, resulting in a buildup of horizontal confining pressures, much higher soil modulus than the original soil, and reducing vertical displacements prior to structural loading.

In wet top feed method, jetting water is used to remove soft material, stabilize the probe hole ensuring the stone backfill reaches the tip of the vibrator. The wet method produces spoils that need to be considered on sites with restricted area or environmentally sensitive areas.

In dry bottom feed method stone backfill is fed directly to the tip of the vibrator using a supply tube.

This method does not introduce water by jetting, which reduces or eliminates the generation of spoils. This treatment can be used below the groundwater table.

It may be necessary to install two to three short aggregate piers at each column location to support the design column load. Upon completion of installing all short aggregate piers, spread and continuous footings would then be constructed on top of the short aggregate piers. A Geopier™ is a proprietary technique, so Geopier™ contractor should perform the actual design of the Geopiers.

The closest Geopier™ and/or impact pier contractor is GeoStructures in Leesburg, Virginia.

Hayward Baker is a provider of vibro-placement stone columns.

We recommend that a combination of short aggregate piers and shallow foundations for the proposed two-story building be design for a preliminary allowable bearing pressure of 3,000 psf.

Based on the assumed maximum load for this building, we estimate piers will typically be 30 inches in diameter and installed to a minimum depth of 10 feet below the bottom of shallow foundation.

6. PAVEMENT

The subsurface soil conditions encountered outside the building pad area were consistent with the conditions found within the building pad area. The existing fill material should be excavated to a minimum depth of 1 foot, proof rolled, and replaced with compacted structural fill material. In addition, a geotextile filter fabric should also be installed between the existing subgrade and the fill material. This improved subsurface can use a design CBR value of ten for flexible pavement design provided that the pavement subgrade will be proof rolled, will incorporate geotextile filter fabric, and will consist of compacted structural fill.

For rigid pavement, if required, a modulus of subgrade reaction of 250 pci is appropriate for compacted structural fill material.

APPENDIX A Page 4

APPENDIX A Page 5

GEOTECHNICAL INVESTIGATION

DOVER AIR FORCE BASE

OUTDOOR RECREATION CENTER (ORC) SITE

DOVER, DELAWARE

U.S. ARMY CORPS OF ENGINEERS

PHILADELPHIA DISTRICT

CONTRACT W912BU-05-D-0006

TASK ORDER 0008, MODIFICATION 0001

Schnabel Reference 06150100.A0

PREPARED FOR

EA Engineering, Science, and Technology

15 LOVETON CIRCLE

SPARKS, MD 21152

AND

U.S. ARMY CORPS OF ENGINEERS

PHILADELPHIA DISTRICT

WANAMAKER BUILDING

100 PENN SQUARE EAST

PHILADELPHIA, PA 19107-3396

June 2007

PREPARED BY

510 East Gay Street, West Chester, Pennsylvania 19380

Phone (610) 696-6066 Fax (610) 696-7771

Bohdan Pazuniak, P.E. Allen W. Cadden, P.E.

Senior Associate Principal

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Project 06150100.A0 / June 14, 2007 Page i Schnabel Engineering North, LLC

GEOTECHNICAL LABORATORY TESTING

DOVER AIR FORCE BASE ORC SITE

DOVER, DELAWARE

TABLE OF CONTENTS

EXECUTIVE SUMMARY ................................................................................................................. iii

I. INTRODUCTION

II. FIELD AND LABORATORY TESTING PROGRAMS

A. Geophysical Field Program B. Field Drilling Program C. Laboratory Testing

III. SUBSURFACE CONDITIONS

A. Generalized Site Geology B. Stratigraphic Conditions C. Ground Water Conditions

IV. DISCUSSION OF PRELIMINARY ANALYSIS

A. Building Pad B. Pavement

V. CONCLUSIONS AND RECOMMENDATIONS

VI. CONSTRUCTION CONSIDERATIONS

VII. LIMITATIONS

TABLES

Table II.1 – Borings Table II.2 – Laboratory Testing Performed on Disturbed Samples Table II.3 – Laboratory Testing Performed on Undisturbed Samples Table II.4 – Laboratory Testing Performed Table III.1 – Shelby Tube Test Results

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FIGURES

Figure 1 – Vicinity Map Figure 2 – Site Plan Figure 3 – Cross Section A-A' Figure 4 – Cross Section B-B' Figure 5 – Cross Section C-C' Figure 6 – Earth Pressure Diagram

APPENDICES

Appendix A: Subsurface Exploration Data Appendix B: Laboratory Test Results

APPENDIX A Page 8

Project 06150100.A0 / June 14, 2007 Page iii Schnabel Engineering North, LLC

EXECUTIVE SUMMARY

This report summarizes Schnabel Engineering North, LLC’s (Schnabel's) field and laboratory evaluation of the subsurface conditions at the proposed Outdoor Recreation Center (ORC) site located on the Dover AFB, bordered on the east by Evreux Street, on the south by Chevron Street, on the west by an existing building (Building 479, The Landings Club), and on the north by a paved parking lot and an existing building. The ORC site previously contained three dormitory buildings that have since been demolished. The site is flat with site grades ranging from EL 20.0 to EL 23.6, and is generally covered with maintained grass. This investigation was completed in conjunction with a detailed civil, environmental, and utility evaluation of the site, performed by EA Engineering, Science, and Technology for the U.S. Army Corps of Engineers (USACE). The purpose of the site investigation was to develop an existing conditions site plan for use in the site development design, and to assess the environmental and geotechnical characteristics of the project site soils.

The proposed ORC will be a single-story, slab-on-grade structure, with a building footprint covering approximately 7,000 square feet (sf). In addition, two other buildings may be developed on-site.

The Future Skills Development Center will have a similar structure and a footprint of approximately 10,800 sf. The car wash structure will cover 2,400 sf. The structure is expected to utilize shallow foundations and wall footings for structural support. Combined dead and live loads for the column loads are anticipated to be on the order of 40 to 60 kips, and wall loads are anticipated to be on the order of one to two kips per linear foot. Grade changes associated with the development are not expected to exceed two feet.

Prior to the commencement of the geotechnical field investigation, Schnabel performed a geophysical survey of the site in order to help locate underground site features and utilities. Both electromagnetic (EM) and ground penetrating radar (GPR) techniques were utilized. Numerous indicators of buried utilities and subsurface features were encountered. The results of the geophysical investigation were utilized to offset some of the proposed test boring locations at the ORC site.

The field investigation program consisted of the completion of 14 drive sample borings extending to depths ranging from 10 to 26 ft each, utilizing a CME-55 truck-mounted drilling rig with a safety hammer. These borings were sampled continuously. At five+ of the locations, supplemental adjacent blind borings were completed to intercept and sample with an undisturbed sampler the thin cohesive strata which were identified in the original borings. All test borings were backfilled with cement/bentonite grout. The top foot of the borehole was filled with topsoil cuttings to allow for grass regeneration. Excess drill cuttings were drummed by the driller for disposal by the Dover AFB maintenance organization.

Geotechnical samples from the field investigation were taken to the Schnabel laboratory in West Chester, Pennsylvania, for further review. Afterwards, the samples were tested at Schnabel’s West Chester laboratory, and shipped to the GeoSystems laboratory in Fort Washington, Pennsylvania.

Laboratory testing per ASTM standards was performed on both jar (disturbed) and undisturbed samples as required by the task order Scope of Work (SOW). Testing included moisture, sieve with and without hydrometer, Atterberg Limits, Unconfined Compression, Unconsolidated Undrained

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(UU), Consolidated Undrained (CU-Bar) triaxial shear, and 1-dimensional consolidation tests with rebound.

Subsurface conditions encountered at the site typically included a surface cover consisting of topsoil, pavement, underlain by fill ranging in thickness from two to four feet, further underlain by alluvial soils. The fill contains probable buried utilities and structures. Below the fill strata, intermixed cohesive and granular alluvium was encountered. The cohesive alluvium ranges from medium stiff to very stiff, and the granular alluvium ranges from medium dense to dense. Schnabel obtained ground water level readings through the casing when encountered at depths of 15.4 to 16.1 ft, EL 6.6 to 7.1.

The undisturbed site soils of Strata B1 and B2 (cohesive and granular alluvial strata, respectively) or compacted structural fill is capable of supporting shallow foundations, spread footings, braced (soil retaining) walls, and slab-on-grade for the proposed structure. Because of the uncontrolled nature of the existing fill, the onsite fill soils of Stratum A should be over-excavated and replaced with structural fill. The on-site fill soil could be reused as structural fill in slab-on-grade areas if an aggressive soil testing/QC program were implemented, the weather conditions are favorable, and the fill met specified gradation limits. However, considering the variable nature of the fill and typical proportions of moisture sensitive materials in the fill, i.e., fine grained soils, it is recommended that the reuse of excavated site soils be limited to non-structural and non-paved applications.

We consider shallow spread footings suitable for support of the proposed structure. Footings bearing on Strata B1 and B2, as well as controlled structural fill may be designed for a net allowable soil bearing pressure of 3,000 pounds per square foot (psf). Interior footing grades may be set at nominal depths below the floor slab. Exterior footings should be founded below a depth of 2.5 ft for frost considerations. Interior footing grades may be set at nominal depths below the floor slab.

Suitable natural soils or compacted structural fill may support the floor slabs. A modulus of subgrade reaction, k, of 150 pounds per cubic inch (pci) may be used in design of floor slabs.

The surficial soils were predominantly fine-grained, with poor drainage characteristics. Therefore, provisions for surface and pavement section drainage should be incorporated into the final pavement design. In addition, geotextile filter fabric should also be utilized as a separation fabric if the pavement granular base is sitting directly on a fine-grained soil subgrade. Assuming that the pavement subgrade will be compacted and proofrolled, then a CBR value of 8 may be utilized for flexible pavement design. A modulus of subgrade reaction, k, of 150 pci may be used in design of rigid pavements.

We are providing this executive summary solely for purposes of overview. Any party that relies on this report must read the full report. This executive summary omits several details, any one of which could be very important to the proper application of the report.

APPENDIX A Page 10

Project 06150100.A0 / June 14, 2007 Page 1 Schnabel Engineering North, LLC

I. INTRODUCTION

In accordance with our subcontract with EA Engineering, Science, and Technology (EA) for Contract W912BU-05-0006, Task Order 0008, Modification 0001, Schnabel Engineering North, LLC (Schnabel), has completed the field subsurface geotechnical investigation and laboratory testing for the proposed Outdoor Recreation Center (ORC) Site at Dover Air Force Base (AFB) in Dover, Delaware.

Environmental screening and sampling of the subsoils were completed at the site to evaluate appropriate disposal of excavated site soils during site development. This environmental sampling was performed by EA in conjuncture with the geotechnical investigation. This screening information is summarized in the ORC Environmental Investigation Report (EA, 2007), which was developed and submitted as a separate report as required by the task order Scope of Work (SOW).

The six-acre ORC site is located on the Dover AFB and is bordered on the east by Evreux Street, on the south by Chevron Street, on the west by an existing building (Building 479, The Landings Club), and on the north by a paved parking lot and an existing building. The ORC site previously contained three dormitory buildings that have since been demolished. The site is flat with site grades ranging from EL 20.0 to EL 23.6, and is generally covered with maintained grass.

The site will contain the future ORC building, as well as the Future Skills Development Center and a car wash structure. The location of the site is presented on the Vicinity Map, Figure 1. The proposed ORC will be a single-story, slab-on-grade structure, with a building footprint covering approximately 7,000 square feet (sf). The Future Skills Development Center will have a similar structure and a footprint of approximately 10,800 sf. The car wash structure will cover 2,400 sf.

Grade changes associated with the site development are not expected to exceed two feet. The ORC structure is expected to utilize shallow pier footings and wall footings for structural support, as well as a slab-on-grade. Combined dead and live loads for the column loads are anticipated to be on the order of 40 to 60 kips, and wall loads are anticipated to be on the order of one to two kips per linear foot. Additional information, beyond what has been presented, has not been provided.

The location of borings, along with other pertinent site information, is presented on the Site Plan, Figure 2.

II. FIELD AND LABORATORY TESTING PROGRAMS

Prior to the commencement of the field investigation, a site specific Health and Safety Plan (HASP) and Work Plan, addressing issues related to performing this subsurface investigation at the Dover Air Force Base, were submitted by EA and approved by the USACE in December 2006. The HASP was required due to the potential of encountering environmental contaminants from previous base operations. EA provided the environmental monitoring during the field operations. This activity includes field screening of extracted soil borings with a photoionization detector (PID). The results of the field screening were minimal, and are discussed in the ORC Environmental Investigation Report (EA, 2007), a separate report required by the task order.

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Project 06150100.A0 / June 14, 2007 Page 2 Schnabel Engineering North, LLC

A. GEOPHYSICAL FIELD PROGRAM

Prior to the commencement of the geotechnical field investigation, Schnabel performed a geophysical survey of the site in order to help locate underground structures, debris and utilities.

Both electromagnetic (EM) and ground penetrating radar (GPR) techniques were utilized. A separate geophysical report was prepared by Schnabel and was a separate deliverable as required by the task order SOW. The results of the geophysical investigation were utilized to assist in locating some of the proposed test boring locations at the ORC site.

B. FIELD DRILLING PROGRAM

Environmental Remediation Contracts, Inc. (ERC) of Delran, New Jersey, drilled 14 drive sample borings to depths of 10 to 26 ft each, utilizing a CME-55 truck-mounted drilling rig with a safety hammer. The hammer drop system utilized a cathead and rope mechanism. These borings were sampled continuously. At five of the locations, supplemental blind borings were completed to intercept and sample thin cohesive strata (which were identified in the original boring) with an undisturbed sampler. These adjacent borings contain the suffix “A.” All test borings were backfilled with cement/bentonite grout upon completion. The top foot of the borehole was backfilled with topsoil cuttings to allow for the grass to regenerate. All remaining cuttings were drummed for disposal by the Dover Air Force Base Maintenance organization.

The original boring locations were determined by the USACE and field-staked by VanDemark and Lynch, the surveyor for the project. Some of the test borings were later shifted to avoid potential buried utilities. The as-built test boring locations were later resurveyed after the field investigation was completed to provide updated plan coordinates and elevations. Specific observations, remarks, and logs for the borings, classification criteria; and sampling protocols are included in Appendix A.

The as-built location and elevation information for these test borings are presented in Table II.1 below:

Table II.1 – Borings

Boring Plan Coordinates Depth Elevation Date Drilled

DVB-15 Northing 410215.5 Easting 636889.1 26 22.0 2/26/2007

DVB-15A Northing 410215.5 Easting 636892.1 5.3 22.0 3/1/2007

DVB-16 Northing 410231.1 Easting 636820.0 10 23.4 3/1/2007

DVB-17 Northing 410303.2 Easting 636827.1 26 23.3 2/26/2007

DVB-18 Northing 410170.9 Easting 636735.3 26 22.7 2/28/2007

DVB-18A Northing 410173.9 Easting 636735.3 7.5 22.7 2/28/2007

APPENDIX A Page 12

Project 06150100.A0 / June 14, 2007 Page 3 Schnabel Engineering North, LLC

Boring Plan Coordinates Depth Elevation Date Drilled

DVB-19 Northing 410304.2 Easting 636600.8 10 23.7 2/28/2007

DVB-19A Northing 410301.2 Easting 636600.8 9 23.7 2/28/2007

DVB-20 Northing 410175.6 Easting 636561.8 26 22.5 3/1/2007

DVB-21 Northing 410223.7 Easting 636640.2 10 23.5 2/28/2007

DVB-22 Northing 410530.5 Easting 636785.8 10 23.3 3/1/2007

DVB-23 Northing 410508.6 Easting 636543.3 10 23.4 2/26/2007

DVB-24 Northing 410421.0 Easting 636746.1 10 23.9 2/28/2007

DVB-25 Northing 410358.3 Easting 636790.8 10 23.9 2/26/2007

DVB-25A Northing 410358.3 Easting 636790.8 4.1 23.9 3/1/2007

DVB-26 Northing 410356.6 Easting 6368681.2 10 23.8 2/28/2007

DVB-27 Northing 410345.1 Easting 636531.5 10 23.4 2/26/2007

DVB-28 Northing 410107.3 Easting 636642.9 10 22.9 2/26/2007

DVB-28A Northing 410103.3 Easting 636645.9 9 22.9 2/28/2007

Note: Test boring locations with the “A” suffix were supplemental blind borings completed to intercept and sample cohesive zones with an undisturbed sampler.

Undisturbed tube samples were collected using brass Shelby Tube samplers per ASTM Standards.

A test pit investigation was completed by the USACE adjacent to DVB-17 to investigate anomalies identified during the geophysical investigation. The test pit was excavated to a depth of five feet below ground surface using a backhoe and operator provided by the Dover Air Force Base Civil Engineering group. An eight-inch terracotta pipe and miscellaneous debris (concrete, glass, wood, etc.) were identified in the test pit at depths of 0.5 to 3.3 ft. These are believed to be remnants of the demolished structure. Two logs (DVP-2A and DVP-2B) of this test pit were generated: one bearing north-south, and the second bearing east-west and intersecting at a point. These logs are included in Appendix A for reference.

C. LABORATORY TESTING

Geotechnical samples from the field investigation were taken to the Schnabel laboratory in West Chester, Pennsylvania, for further review and laboratory assignment. The samples were then taken to GeoSystems in Fort Washington, Pennsylvania, for testing. Laboratory testing was completed on

APPENDIX A Page 13

Project 06150100.A0 / June 14, 2007 Page 4 Schnabel Engineering North, LLC both jar (disturbed) and undisturbed samples as requested in the contract per ASTM standards.

Representative jar samples of soil layers were chosen to test for moisture content, Atterberg Limits, organic content, specific gravity, and sieve tests. Test results are shown in Appendices A and B.

Undisturbed sample laboratory testing was performed on the six samples specified by the USACE in the task order SOW and in accordance with later discussions with the USACE. Testing included moisture, sieves without hydrometer, Atterberg Limits, Unconfined Compression, Unconsolidated Undrained (UU), Consolidated Undrained (CU-Bar) triaxial shear, and 1-dimensional consolidation tests with rebound according to ASTM standards. Tables II.2, II.3, and II.4 show the tests performed. Individual test results follow the summary tables in Appendix B.

Table II.2 – Laboratory Testing Performed on Disturbed Samples

Boring

Depth Sample

Collected (ft)

Stratum Tests Completed

Moisture Content Sieve Sieve with

Hydrometer Atterberg

Limits

DVB-15 2-4 B2 x x x

DVB-15 6-7 B1 x x x

DVB-15 8-10 B2 x x

DVB-15 16-18 B2 x x

DVB-16 2-4 B1 x x x

DVB-16 4-6 B2 x x

DVB-17 2-4 B2 x x x

DVB-17 4-6 B2 x x

DVB-17 8-10 B2 x x

DVB-17 16-18 B2 x x

DVB-18 2-4 A x x

DVB-18 8-10 B2 x x

DVB-18 12-14 B2 x x

DVB-18 18-20 B2 x x

DVB-19 2-4 A x x

DVB-19 4-6 B2 x x x

DVB-20 0-2 A x x x

DVB-20 4-6 B2 x x

DVB-20 10-12 B2 x x

DVB-20 12-14 B2 x x

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Depth Sample

Collected (ft)

Stratum Tests Completed

Moisture Content Sieve Sieve with

Hydrometer Atterberg

Limits DVB-21 2-4 A x x

DVB-21 4-6 B1 x x

DVB-21 6-8 B2 x x x

DVB-22 0-2 A x x

DVB-22 4-6 B2 x x x

DVB-22 6-8 B2 x x

DVB-23 0-2 A x x

DVB-23 2-4 B2 x x

DVB-23 6-8 B2 x x

DVB-24 0-2 A x x

DVB-24 2-4 B1 x x x

DVB-24 6-8 B1 x x x

DVB-25 0-2 A x x

DVB-25 4-6 B2 x x x

DVB-25 8-10 B1 x x x

DVB-26 0-2 A x x

DVB-26 2-4 A x x

DVB-26 6-8 B1 x x x

DVB-27 2-4 A x x

DVB-27 4-6 B2 x x

DVB-27 6-8 B1 x x x

DVB-28 4-6 B2 x x

DVB-28 6-8 B1 x x x

DVB-28 8-10 B1 x x x

Total 44 41 3 16

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Table II.3 – Laboratory Testing Performed on Undisturbed Samples

Depth Sample

Collected (ft)

Stratum Tests Completed

M oi st ur e C on te nt

Si ev e

A tt er be rg L im its

U nc on fin ed C om pr es si on

U nc on so lid at ed U nt ra in ed

(U U

C on so lid at ed

U nd ra in ed -B ar

1- D

C on so lid at io n w

/R eb ou nd

DVB-15A 4-5.3 B1 x x x x DVB-18A 5.5-7.5 B1 x x x x x DVB-19A 7.5-9 B2 x x x x x DVB-20 6-8 B1 x x x x

DVB-25A* 2.5-4.1 B1 x x x DVB-28A 7-9 B1 x x x x x

Total 6 6 6 2 2 4 Notes: 1. Every consolidation, Unconfined Compression, and UU test includes density and moisture content.

2. Every consolidation also includes specific gravity, as well as time series for some or all the load increments.

* Upon opening of the Shelby Tube, the sample was found to be too disturbed for testing.

A listing of all the tests completed is as follows:

Table II.4 – Laboratory Testing Performed

Proposed Completed Remarks

Moisture Content 44 44 Moisture Content & Density 6 4

Atterberg Limits 24 22 Note (1) Sieve Analysis 47 47

Sieve and Hydrometer 3 3 Specific Gravity 0 5 Done w/consolidation

Unconfined Compression 3 5 Unconsolidated Undrained 2 1 Note (2)

CU-Bar 1 0 Disturbed sample Consolidation w/Rebound 4 4

Notes: 1. Insufficient adequate sample(s) were collected to complete intended number of tests.

2. Six consolidation and two UU tests were requested but Shelby Tube sample (DVB-

18A) consisted of sand and could not be tested.

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III. SUBSURFACE CONDITIONS

A. GENERALIZED SITE GEOLOGY

We reviewed existing geologic data and available information, including the Delaware Geological Survey (DGS) map of the site. Based on our review and field observations, the project area is underlain by the alluvial deposits of the Columbia Formation, further underlain by the sandy silt and sand deposits of the Calvert Formation, both of which are situated in the Coastal Plain Geologic Province. Depth to bedrock is estimated to be on the order of 2,000 to 3,000 ft.

B. STRATIGRAPHIC CONDITIONS

We have characterized the following generalized subsurface soil stratigraphy based on the boring data presented in Appendix A. Surface cover across the site ranged from asphalt (4" to 5") overlaying a granular sub base (3"), to topsoil (2" to 4"). Cross Sections are presented on Figures 3, 4 and 5.

Stratum A – Fill

In all of the test borings a fill stratum was encountered, extending to depths of 2 to 4 ft below existing grade. The fill soil ranged in description from sandy lean clay to silty clay to sandy silt to clayey/silty sand (CL, CL-ML, ML, SM and SC). The measured natural moisture content ranged from 6.0 to 17.2 percent. Based on the Standard Penetration Tests performed, this stratum is either medium stiff to very stiff or loose to medium dense in consistency: N = 5 to 27.

Stratum B1 – Cohesive Alluvial

Below the fill soils of Stratum A, in all but two borings (DVB-22 and DVB-23), the borings encountered a cohesive alluvial stratum consisting of yellow-brown and red-brown silt and clay (CL, CL-ML, and MH) with varying amounts of sand to depths of 5 to 10 ft. Often this stratum was interlayered with the granular alluvium of Stratum B2, as described below. The Stratum B1 soils are generally of moderate plasticity having liquid limits between 23 and 36, and plasticity indices of 7 to 18. The natural moisture contents measured were near the plastic limit: about 20 percent. Elastic silt (MH) was encountered at one isolated location (DVB-28) which is outside of the building area. Based on the Standard Penetration Tests performed, this stratum is generally stiff to very stiff: N = 9 to 26.

Stratum B2 – Granular Alluvial

Below the cohesive soils of Stratum B1, and sometimes interlayered with them, the borings encountered a granular alluvial stratum consisting of dark brown and orange-brown clayey, silty, well graded or poorly graded sand (SC, SM, SW-SM, SP-SC, SP-SM and SP) with occasional gravel, to the termination depths of the deeper borings. Based on the Standard Penetration Tests performed, this stratum is generally medium dense to dense: N = 4 to 70.

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Undisturbed soil samples from this stratum were tested for consolidation and strength characteristics, the results of which are presented in Table III.1.

Table III.1 – Shelby Tube Test Results

Unc.

Compr. UU

Boring Depth (ft) Stratum Cc' Cr' Pc

(tsf) OCR Su (tsf) c (psi)

(deg.)

DVB-15A1 4-5.3

B1 1.56

DVB-18A 5.5-7.5

B2 0.18 0.004 5.3 12.6 3.7 27

DVB-19A 7.5-9

B1 0.111 0.003 3.0 6.25 0.44

DVB-202 6-8

B1 0.20 0.006 6.5 15.5

DVB-25A3 2.5-4.1

B1

DVB-28A 7-9

B1 0.12 0.014 5.5 11.5 14.3 0

Notes:

Cc' = Compression Ratio Cr' = Recompression Ratio Pc = Preconsolidation Stress Su = Shear Strength c = Cohesion � = Internal Friction

1. DVB-15A consolidation sample was damaged during testing; no results available.

2. DVB-20 sample quality was too poor to provide representative CU-Bar results; therefore, although CU-

Bar testing was completed, the results are not provided.

3. DVB-25A, unable to trim specimens for testing due to the condition of the sample.

C. GROUND WATER CONDITIONS

The logs note ground water level readings obtained in the borings when encountered and at completion. In the deeper borings, we obtained ground water level readings through the casing when encountered at depths of 15.4 to 16.1 ft, corresponding to EL 6.6 to 7.1 MSL. These levels may or may not represent stabilized water level readings, as the borings were backfilled with grout upon completion.

The final design should anticipate fluctuations in the water table depending upon variations in precipitation, surface runoff, pumping, evaporation, stream levels and similar factors.

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IV. DISCUSSION OF PRELIMINARY ANALYSIS

A. BUILDING PAD

The undisturbed site soils of Strata B1 and B2 or compacted structural fill is capable of supporting spread foundations and slab-on-grade for the proposed structure. Because of the uncontrolled nature of the fill placement, the on-site fill soils of Stratum A should be over-excavated and replaced with structural fill. The on-site fill soil could be reused as structural fill in slab-on-grade areas if an aggressive soil testing/QC program were implemented, the weather conditions are favorable, and the fill met specified gradation limits. However, considering the variable nature of the fill and typical proportions of moisture sensitive materials in the fill, i.e., fine grained soils, it is recommended that the reuse of excavated site soils be limited to non-structural and non-paved applications.

The medium dense to dense granular, as well as the medium stiff and stiff natural soil deposits encountered at the site, are typical throughout the greater Dover area. The Dover AFB has a history of successfully constructing relatively lightly loaded buildings on spread foundations in these conditions. Design and construction with spread foundations have been historically accomplished using relatively low allowable bearing pressures to limit anticipated settlement in these loose soil conditions.

We consider shallow spread footings suitable for support of the proposed structure. Footings bearing on Strata B1 and B2, as well as controlled structural fill may be designed for a net allowable soil bearing pressure of 3,000 pounds per square foot (psf). Interior footing grades may be set at nominal depths below the floor slab. Exterior footings, or those which may be exposed to climate variation, should be founded below a depth of 2.5 ft for frost considerations. Interior footing grades may be set at nominal depths below the floor slab as determined by the design engineers.

Settlements of shallow foundations supported on suitable natural soils and on properly placed compacted structural fill are not expected to exceed about one (1) inch. Differential settlements between similarly loaded footings are not expected to exceed about half this value.

B. PAVEMENT

Test borings completed outside of the building pad area were found to be similar to those encountered in the building pad. The change in pavement grade is expected to be minor. Therefore, the encountered surficial soil will correspond to the pavement subgrade. In general, the surficial soils were predominantly fine-grained, with poor drainage characteristics. Therefore, provisions for adequate surface and pavement section drainage should be incorporated into the final pavement design. In addition, geotextile filter fabric should also be utilized if the pavement granular base is placed directly on a fine-grained soil subgrade. Assuming that the pavement subgrade will be compacted and proofrolled, then a CBR value of eight may be utilized for flexible pavement design.

For rigid pavement, if required, a modulus of subgrade reaction of 150 pci is appropriate due to compacted on-site soils. If porous aggregate is utilized to provide drainage, a higher modulus value may be utilized.

V. CONCLUSIONS AND RECOMMENDATIONS

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Based on the data obtained in the field and laboratory testing programs, available building and site information and subsequent geotechnical analysis, the following conclusions and recommendations are presented.

1. In the building areas, the contractor should remove existing topsoil and buried structures, and undercut existing fill from the building area. Our subsurface exploration indicated topsoil and/or fill depths of up to four feet below the ground surface. This undercut should extend at least five feet horizontally beyond the projected building dimensions. The fill undercut should be monitored and approved by the geotechnical engineer. Before any fill placement, the geotechnical engineer should evaluate the soils for suitability based on observations of proofrolling with a loaded dump truck. The contractor should excavate areas exhibiting excessive pumping, weaving, or rutting, and replace these areas with additional compacted structural fill. The contractor should also proof-roll final pavement subgrades under the observation of the geotechnical engineer to evaluate suitability of these subgrades.

2. The contractor may use the non-organic granular portion of material excavated as compacted structural fill if stripping and earthwork operations occur during an extended period of warm, dry weather. The on-site fill soil could be reused as structural fill in slab-on-grade areas if an aggressive soil testing/QC program were implemented, the weather conditions are favorable, and the fill met specified gradation limits. However, considering the variable nature of the fill and typical proportions of moisture sensitive materials in the fill, i.e., fine grained soils, it is recommended that the reuse of excavated site soils be limited to non-structural and non-paved applications.

3. Some existing underground structures or debris may be present on the site. Therefore, grading activities may encounter buried foundations and other associated debris. We recommend the complete removal of existing foundations from within the proposed building area. The contractor should remove existing foundations and walls in the proposed pavement areas to at least two feet below the design pavement subgrade level. Existing utilities and drainage structures within the building area should also be rerouted or removed, and the excavations backfilled with compacted structural fill.

4. We recommend evaluating undercut volumes by cross sectioning. Other methods of calculating volumes of undercut, such as counting trucks, are less accurate and generally result in additional expense.

5. For areas supporting foundations, compacted structural fill should consist of material classifying GW, GP, GM, SW, SP, or SM, and dual-classifications when the percent fines is between 5 and 12 percent. These gradations fall under Delaware Department of Transportation, Select Borrow, Type G (all gradations except VI), and are listed in Table 209-A of the most recent Specifications. In all other areas, compacted structural fill should consist of material classifying ML, CL, ML-CL, SC, SM, SP, SW, GC, GM, GP, or GW per ASTM D2487. Non-organic, on-site soils are expected to meet this criterion. Compacted structural fill should be placed in maximum eight-inch thick horizontal, loose lifts and should be compacted to at least 95 percent of maximum dry density per ASTM D1557, Modified Proctor.

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6. We consider shallow spread footings suitable for support of the proposed structure. Footings should be supported on suitable natural soils of Strata B1 and B2, and on compacted structural fill. Footings bearing on Stratum B1, B2 and controlled structural fill may be designed for a net allowable soil bearing pressure of 3,000 pounds per square foot (psf). This bearing pressure provides a factor of safety of at least 3.0 against general shear failure.

Where design loads include combinations of transient wind and/or earthquake loads that result in a non-uniform soil bearing stress distribution beneath the footing, the maximum allowable soil bearing pressure may be taken as 1.33 times the net allowable soil bearing pressure given above.

7. Settlements of shallow foundations supported on suitable natural soils and on properly placed compacted structural fill are not expected to exceed about one (1) inch. Differential settlements between similarly loaded footings are not expected to exceed about half this value. Minimum widths of 12 and 24 inches should be maintained for wall and column footings, respectively, for shear considerations. Interior footing grades may be set at nominal depths below the floor slab. Exterior footings, or those which may be exposed to climate variation, should be founded below a depth of 2.5 ft for frost considerations.

8. Final grades should allow positive drainage away from the structure so that water does not accumulate around the foundation. Positive site drainage should be maintained on the exposed building and pavement area subgrades throughout the construction activities.

9. Suitable natural soils or compacted structural fill may support the floor slabs. A modulus of subgrade reaction, k, of 150 pci may be used in design of floor slabs. A four-inch thick layer of crushed stone or washed gravel capillary moisture barrier should underlie floor slabs on grade. Moisture barrier material should consist of Delaware Department of Transportation No. 57 stone. The contractor should compact the stone in place by at least two passes with suitable vibratory compaction equipment.

10. We consider that the loading dock walls, if required, are braced. The wall design should use an equivalent fluid pressure of 55 H psf (where H is the height of the wall in feet) for walls backfilled with on-site soil as shown on Figure 6, which utilizes a behind the wall drainage panel system. Where applicable, the design should consider surcharge loads using a rectangular earth pressure distribution. The surcharge pressure ordinate should be obtained by multiplying the surface surcharge pressure, q, by 0.47. These design parameters do not consider hydrostatic pressure, since we recommend subdrainage behind the walls. Basement walls should be backfilled as recommended below. The design should provide subdrainage behind the basement (loading dock) walls. Subdrainage should consist of perimeter subdrains located on top of the wall footing, next to the wall. Subdrains should consist of four-inch slotted, corrugated polyethylene tubing per ASTM F405 surrounded by at least six inches of No. 78 aggregate. A drainage geotextile consisting of Mirafi 140N or equivalent should wrap around the aggregate. The contractor should daylight or outlet subdrains to a convenient sump or storm sewer.

11. Geocomposite drainage panels consisting of Miradrain G100N or equivalent are recommended when on-site soils are used as wall backfill. Drainage panels should be placed along the entire wall face to within 1.5 ft of finished grade. The contractor should bind the

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12. Alternatively, a free-draining backfill can be used in lieu of a drainage panel system. This would include non-plastic material classifying SP-SM, SW-SM, SP, SW, GW-GM, GP-GM, GP or GW according to ASTM D2487. This classification includes open-graded crushed stone such as AASHTO M43 No. 78 or No. 57. The contractor should place free-draining backfill in maximum eight-inch thick loose lifts, and compact each lift to at least 95 percent of maximum dry density per ASTM D698, Standard Proctor, or to 70 percent relative density per ASTM D4253 and D4254. The contractor should place free-draining backfill in maximum eight-inch thick lifts, and compact each lift using suitable vibratory equipment.

13. We have evaluated the Seismic Site Class for this project according to IBC Section 1615

(2003). We recommend Site Class D be used for seismic design on this project. This Site Class was evaluated based on field and laboratory test results.

14. The pavement section(s) should be designed to provide adequate base drainage, and should also incorporate a geotextile filter separation layer between the pavement section and the pavement subgrade. Given that the pavement subgrade has been compacted and successfully proof-rolled, a CBR value of 8 should be utilized for the design of flexible pavements. If rigid pavement sections are utilized, a modulus of subgrade reaction of 150 pci may be utilized. All pavement construction and materials should conform to the requirements of the U.S. Air Force and the USACE.

VI. CONSTRUCTION CONSIDERATIONS

1. The test boring data indicates the approximate depth of topsoil and fill, based on our visual identification procedures. In the pavement area, the depth of stripping necessary to provide a suitable base for placement and compaction of structural fill or for pavement subgrade preparation consists of the topsoil and existing pavement. In the building area, the stripping and undercutting depth includes the total depth of fill. For areas underlain by foundations, the USACE undercut specifications will be utilized.

2. The on-site soils are susceptible to moisture changes, will be easily disturbed, and will be difficult to compact under wet weather conditions. Drying and reworking of the soils are likely to be difficult during wetter winter months. We recommend that the earthwork phases of this project be performed during the warmer, drier times of the year to limit the potential for disturbance of on-site soils.

3. Traffic on stripped or undercut subgrades should be limited to reduce disturbance of underlying soils. Also, using lightweight, track-mounted dozer equipment for stripping will limit the disturbance of underlying soils, and may reduce the undercut volume needed. The contractor should provide site drainage to maintain subgrades free of water and to avoid saturation and disturbance of the subgrade soils before placing compacted structural fill, pavement base course or moisture barrier material.