VA245-17-B-0086-A00007007.pdf

Geotechnical Engineering Report VA Huntington Facility Generator Project

Huntington, West Virginia

January 5, 2017

Terracon Project No. N2165135

Prepared for:

GUIDON Design, Inc.

Indianapolis, IN

Prepared by:

Terracon Consultants, Inc.

Charleston, West Virginia

Terracon Consultants, Inc. 912 Morris Street Charleston, West Virginia

P [304] 344 0821 F [304] 342 4711 terracon.com

GUIDON Design, Inc.

905 N. Capitol Avenue

Suite 100

Indianapolis, IN 46204

Attn: Mr. Mark VanderWoude, P.E.

Project Manager / Structural Division Lead

P: [317] 800-6388 ext. 119

E: mvanderwoude@guidondesign.com

Re: Geotechnical Engineering Report

VA Huntington Facility Generator Project

Huntington, West Virginia

Dear Mr. VanderWoude:

We are pleased to present our report of geotechnical study for the VA Huntington Facility

Generator project located in Huntington, West Virginia. This study was performed in general accordance with our proposal dated November 7, 2016.

Terracon has previously issued a Geotechnical Report for the area to the south of the existing VA facility (our report dated August 4, 2016). This latest report is for the geotechnical exploration to the northeast of the previous location and includes findings of our subsurface exploration, results of our analyses, conclusions and recommendations addressing site grading and foundation design/construction considerations for the generator facility at the site.

We appreciate the opportunity to be of service to you on this project. Please contact us concerning any questions that may arise during review of the report, or if you require additional information as you proceed through the final design and construction stage of this project.

Sincerely, Terracon Consultants, Inc.

Alma K. Baratta, P.E. Prasad S. Rege, P.E.

Geotechnical Department Manager Senior Principal/Division Manager mailto:bjbonham@aep.com rneupane Text Box

FOR

TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY ............................................................................................................ i

1.0 INTRODUCTION

2.0 PROJECT INFORMATION

Project Description

Site Location and Description

3.0 SUBSURFACE CONDITIONS

Geology

Typical Profile

Groundwater

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

Geotechnical Considerations

Site Preparation and Earthwork

Temporary Excavations/Retention System

Structural Fill Requirements

Structural Fill Placement and Compaction Requirements

Grading and Drainage

Lateral Earth Pressures for North and Western Building Walls

Drilled Shaft Foundations

Soldier Pile and Lagging Retaining Wall for Southern Retaining Wall

Seismic Site Classification

5.0 GENERAL COMMENTS

APPENDIX A – FIELD EXPLORATION

Exhibit A-1 Site Location

Exhibit A-2 Exploration Plan

Exhibit A-3 Field Exploration Description

Exhibits A-4 to A-15 Boring Logs

APPENDIX B – LABORATORY INFORMATION

Exhibit B-1 Laboratory Testing

Exhibit B-2 Atterberg Limits

APPENDIX C – SUPPORTING INFORMATION

Exhibit C-1 General Notes

Exhibit C-2 Unified Soil Classification System Summary

Exhibit C-3 Description of Rock Properties

Exhibit C-4 Conceptual Drawings

VA Huntington Facility Generator Project ■ Huntington, West Virginia January 5, 2017 ■ Terracon Project No. N2165135

Responsive ■ Resourceful ■ Reliable i

EXECUTIVE SUMMARY

A geotechnical engineering study has been completed for the VA Huntington Facility Generator

Project located in Huntington, West Virginia. Six (6) geotechnical test borings were extended to depths ranging from about 31.5 to 50.5 feet below the existing ground surface. These borings are in addition to the six (6) borings performed as part of our original Geotechnical Report, dated August

4, 2016.

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

■ Terracon previously issued a geotechnical report for the area to the south of the existing

VA facility (our report dated August 4, 2016). Due to slope stability issues at the initial proposed section of the hillside, Guidon Design proposed to relocate the generator facility to the northeast of the previous location and requested design of an approximately 7-foot tall retaining wall located in the vicinity of our previous exploration. Borings B-1 through B-

6 were performed in the area of our original exploration, documented in our August 4, 2016 report. Borings B-7 through B-12 have been performed in the area of the relocated generator structure, to the north and east of the original location.

■ The borings encountered existing fill material consisting of sandy lean clay with varying amounts rock fragments and organic material. This existing fill material was underlain by sandy shale, claystone, and sandstone bedrock, which was encountered at depths ranging from about 7.5 to 15 feet below the existing ground surface in Borings B-1 through

B-6, and 15 to 31.5 feet below the existing ground surface in Borings B-7 through B-12.

■ The proposed building will have two levels, with the upper level matching the existing ground surface (elevation of about 872 feet) surrounding the VA facility. The lower level will be notched into the hillside and will require cutting into the hillside to create space for its construction. The existing slope will continue below the lower level of the structure.

We anticipate the lower level of the generator structure will be located at approximately elevation 857 feet.

■ In order to retain the cut on the northern and western sides of this structure, a cast-in-place wall is being proposed by Guidon. However, a temporary retention system will be required prior to construction of this wall in order to prevent undermining of structures located on top of the slope while the excavation activities occur.

■ Based on the conditions encountered in the borings, we anticipate existing fill will be exposed at the lower level of the structure. The existing fill is not considered suitable for direct structure support. We recommend supporting all of the structure walls and slabs on drilled shaft foundations. We recommend that each drilled shaft foundation element be at

Responsive ■ Resourceful ■ Reliable ii least 1.5 feet in diameter and extend a minimum of 3 feet into bedrock. The actual embedment of the shafts into the bedrock may be greater based on design lateral loading considerations.

■ The north and western cast-in-place walls, supported on drilled shafts, should be designed to incorporate the associated lateral and axial loadings of the proposed structure and lateral loads associated with retained soils. Temporary excavation support, as indicated above, is anticipated prior to construction of these wall.

■ Due to the slope and the slope stability issues in the area of our prior exploration, we recommend that the approximately 7-foot tall retaining wall consist of a soldier pile and lagging wall supported in the underlying sedimentary bedrock.

■ Based on boring information, a portion of the proposed excavations is anticipated to extend into shale bedrock. It is anticipated the decomposed, severely weathered bedrock can be mechanically ripped. Deeper excavation into the bedrock will require the use of heavy-duty excavation equipment to facilitate rock break-up and removal. Jack-hammering and rock chisels may be required in utility excavations where working space will be limited. Consideration should be given to the location and invert elevations of utilities planned for the project to reduce the impacts of difficult excavation. Final elevations should be chosen to reduce the amount of potential bedrock excavation.

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

Comments should be read for an understanding of the report limitations.

Responsive ■ Resourceful ■ Reliable 1

GEOTECHNICAL ENGINEERING REPORT

VA HUNTINGTON FACILITY GENERATOR PROJECT

HUNTINGTON, WEST VIRGINIA

1.0 INTRODUCTION

This report presents the results of our geotechnical engineering services performed for the VA

Huntington Facility Generator project located in Huntington, West Virginia. Our geotechnical engineering exploration for this project included the advancement of six (6) test borings, designated B-7 through B-12, to depths ranging from about 31.5 to 50.5 feet below the existing surface grade. These borings are in addition to the six (6) borings performed as part of our original

Geotechnical Report, dated August 4, 2016 (Borings B-1 through B-6). Logs of all of the borings and a Boring Location Plan (Exhibit A-2) are included in Appendix A. Descriptions of the field exploration are also included in Appendix A.

Specifically, this report provides information and geotechnical engineering recommendations relative to:

Subsurface soil conditions Groundwater conditions

Earthwork Foundation design and construction

Seismic considerations

2.0 PROJECT INFORMATION

Project Description

ITEM DESCRIPTION

Site layout See Appendix A, Exhibit A-2, Exploration Plan; See Appendix C, Exhibit C-

4 for Conceptual Drawings

Project information

Provided information indicates the upper level of the structure will house three generator units, and the lower level will contain fuel tanks below each of the generators. A switch gear building is also anticipated. Anticipated information for each of the structures are:

Generator units – 40 feet by 15 feet each

Switch gear building – 40 feet by 20 feet

Fuel storage tank – possibly Convault™ above ground tank

■ The weight has not been provided, but is anticipated to be heavy.

Responsive ■ Resourceful ■ Reliable 2

■ Spill containment system will be required.

Screening wall between the prepackaged units and the rest of the campus for aesthetics.

The structure is anticipated to consist of an upper and lower level with plan dimensions of about 40 feet by 70 feet. The proposed generator building will be located on the side of an existing hillside just east of the existing VA facility. The proposed building will have two levels with the upper level matching the existing ground surface (elevation of about 872 feet) surrounding the VA facility. The lower level will be notched into the hillside and will require cutting into the hillside to create space for its construction.

The existing slope will continue below the lower level of the structure. We anticipate the lower level of the generator structure will be located at approximately elevation 857 feet. In order to retain the cut on the north and western sides of this structure, a cast-in-place wall is being proposed by

Guidon. However, a temporary retention system will be required prior to construction of this wall in order to prevent undermining of structures located on top of the slope while the excavation activities occur.

Additionally, a retaining wall, approximately 7 feet in height, with a surcharge load of 200 psf will be constructed in the area of our previous exploration, located south of the VA facility.

Proposed site grading

Up to approximately 15 feet of excavation is anticipated for construction of the generator support structure. We anticipate the upper level of the structure to be at about 872 feet and the lower level of the structure will be at approximately elevation 857 feet. Proposed finished floor elevations were not available at the time of this report.

Site Location and Description

Location

Site is located at the east end of the VA Medical Center campus in

Huntington, West Virginia.

GPS coordinates: 38.376478°, -82.515483°

Existing site features The proposed structure is being constructed immediately east of an area which is currently pavements and utilities on a vegetated hillside.

Existing topography

The existing pavement area north and west of the proposed generator location is at approximate elevation 872 feet. The hillside slopes downward to the south and east at an approximate 2H:1V slope.

Responsive ■ Resourceful ■ Reliable 3

3.0 SUBSURFACE CONDITIONS

Geology

Based on review of the West Virginia Geologic and Economic Survey, the local geology in the vicinity of the site can be generalized as follows:

Group Description

Conemaugh Group

(Pennsylvanian)

A review of geologic literature indicates that the site is located within an area having cyclic sequences of red and gray shale, siltstone, and sandstone, with thin layers of limestone and coal.

The Conemaugh Group is mostly non-marine and may be divided into Casselman and Glenshaw Formations. The

Conemaugh Group extends from the base of the Pittsburg coal to the top of the Upper Freeport Coal and includes the Elk Lick, Bakerstown, and Mahoning coals. This group also contains the

Ames and Brush Creek Limestones.

According to an online review of the West Virginia Geological and Economic Survey (WVGES)

Interactive Coal Bed Mapping Project, there is no commercial-scale underground or surface mining mapped within the proposed project location.

The WVGES maintains a database of permitted surface, underground, and abandoned mines spatially referenced on maps of differing scales. Due to the length of time that mining has been performed in West Virginia, some mining occurred with limited documentation. The lack of identified mines in any area of the proposed development does not indicate a definite “mine free” area. It is possible that the timing or scale of underground mining may not have required notification of state agencies, thus no record would be available.

Typical Profile

Conditions encountered at the boring locations are indicated on the boring logs. Stratification boundaries on the boring logs represent the approximate location of changes in soil types; in situ, Responsive ■ Resourceful ■ Reliable 4 the transition between materials may be gradual. Details for the borings can be found on the boring logs in Appendix A of this report.

Borings B-1 through B-6:

Stratum

Approximate Depth to

Bottom of Stratum

(feet)

Material Description Consistency/

Density/Hardness

1 7.5 to 15 Fill: Sandy lean clay with varying amounts of rock fragments and organic material Not applicable

2 Undetermined1 Sandy shale, claystone, and sandstone bedrock

Extremely weak to medium strong

1. Borings terminated within this stratum at depths ranging from 35 to 55 feet below existing grade.

Borings B-7 through B-12

Stratum

Approximate Depth to

Bottom of Stratum

(feet)

Material Description Consistency/

Density/Hardness

1 15 to 31.5 Fill: Sandy lean clay with varying amounts of rock fragments and organic material Not applicable

2 Undetermined1 Sandy shale, shale, claystone, and sandstone bedrock

Extremely weak to medium strong

2. Borings terminated within this stratum at depths ranging from 31.5 to 50.5 feet below existing grade.

Groundwater

The boreholes were observed during drilling operations for the presence and level of groundwater.

The test boring was backfilled with auger cuttings upon completion. Water was not encountered in any of the borings during drilling operations and upon completion of drilling.

Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the borings were performed. In addition, perched or trapped water can develop over low permeability soils or within granular seams. Water for rock coring was introduced into the boreholes, which will affect the water levels measured at the completion of drilling. Therefore, groundwater levels during construction or at other times in the life of the structure may be higher than the levels indicated on the boring logs. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project.

Responsive ■ Resourceful ■ Reliable 5

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

Geotechnical Considerations

Terracon previously issued a geotechnical report for the area to the south of the existing VA facility

(our report dated August 4, 2016). Due to slope stability issues at the initial proposed section of the hillside, Guidon Design proposed to relocate the generator facility to the northeast of the previous location and requested design of an approximately 7-foot tall retaining wall located in the vicinity of our previous exploration. Borings B-1 through B-6 were performed in the area of our original exploration, documented in our August 4, 2016 report. Borings B-7 through B-12 were performed in the area of the relocated generator structure, to the northeast of the original location.

The borings encountered existing fill material consisting of sandy lean clay with varying amounts rock fragments and organic material. This existing fill material was underlain by sandy shale, claystone, and sandstone bedrock, which was encountered at depths ranging from about 7.5 to

15 feet below the existing ground surface in Borings B-1 through B-6, and 15 to 31.5 feet below the existing ground surface in Borings B-7 through B-12.

The proposed building will have two levels, with the upper level matching the existing ground surface (elevation of about 872 feet) surrounding the VA facility. The lower level will be notched into the hillside and will require cutting into the hillside to create space for its construction. The existing slope will continue below the lower level of the structure. We anticipate the lower level of the generator structure will be located at approximately elevation 857 feet. In order to retain the cut on the northern and western sides of this structure, a cast-in-place wall is being proposed by Guidon. However, a temporary retention system will be required prior to construction of this wall in order to prevent undermining of structures located on top of the slope while the excavation activities occur.

Based on the conditions encountered in the borings, we anticipate existing fill will be exposed at the lower level of the structure. The existing fill is not considered suitable for direct structure support. We recommend supporting all of the structure walls and slabs on drilled shaft foundations. We recommend that each drilled shaft foundation element be at least 1.5 feet in diameter and extend a minimum of 3 feet into bedrock. The actual embedment of the shafts into the bedrock may be greater based on design lateral loading considerations.

The north and western cast-in-place walls supported on drilled shafts should be designed to incorporate the associated lateral and axial loadings of the proposed structure and lateral loads associated with retained soils. Temporary excavation support, as indicated above, is anticipated prior to construction of the wall.

Responsive ■ Resourceful ■ Reliable 6

Due to the slope and the slope stability issues in the area of our prior exploration, we recommend the approximately 7-foot tall retaining wall consist of a soldier pile and lagging wall supported in the underlying sedimentary bedrock.

Based on boring information, a portion of the proposed excavations is anticipated to extend into shale bedrock. It is anticipated the decomposed, severely weathered bedrock can be mechanically ripped. Deeper excavation into the bedrock will require the use of heavy-duty excavation equipment to facilitate rock break-up and removal. Jack-hammering and rock chisels may be required in utility excavations where working space will be limited. Consideration should be given to the location and invert elevations of utilities planned for the project to reduce the impacts of difficult excavation. Final elevations should be chosen to reduce the amount of potential bedrock excavation.

Our detailed foundation design and construction, as well as earthwork related recommendations are presented in the sections below.

Site Preparation and Earthwork

As indicated before, construction is anticipated to involve cutting into the existing hillside in order to construct the proposed structure. Therefore, it is recommended that the initial activity at the site prior to commencement of the cutting should include construction of a temporary retaining wall to allow top-down construction method. Once the temporary wall is installed, the existing overburden in front of the wall in the cut area can be excavated. Once the excavation is performed, installation of the drilled shafts for support of the proposed structure should begin.

We have recommended that the lowest level slabs should be of “structural slab” type supported on grade beams which are, in turn, supported on deep foundation elements. However, in order to provide suitable subgrade conditions for construction and support of structural fill, all structural areas should be carefully proofrolled under close observation by geotechnical personnel following the installation of temporary earth retention systems and excavations for the generator structure.

Proofrolling should be accomplished using a pneumatic-tired, fully loaded minimum 20 ton tandem-axle dump truck. Soft or yielding areas should be undercut or stabilized. The proofrolling program should consist of a minimum of 3 passes by the proofrolling equipment. The stabilization and suitability of this subgrade is recommended to receive structural backfill and should be monitored by a representative of the Geotechnical Engineer. Actual undercut/stabilization depths should be determined based on the results of the proofrolling and testing during construction.

After proofrolling and prior to the placement of structural fill in areas below design grade, the subgrade should be scarified, moisture conditioned and recompacted to the density recommended in Section 4.2.3 Structural Fill Placement and Compaction Requirements below. This process will further help to delineate soft or disturbed areas. Unstable areas identified

Responsive ■ Resourceful ■ Reliable 7 during scarification and recompaction should be undercut to expose stable material. We recommend an aggregate base course with a minimum thickness of 4 inches comprised of compacted granular material be constructed below the floor slab subgrade elevation.

Temporary Excavations/Retention System

It is expected that the excavation related to the construction of the generator structure will be performed initially. Due to the site constraints associated with existing infrastructure (pavements, structures, utilities, etc.), open cut excavations will likely not be feasible and temporary earth retention system(s) should be considered.

These retention systems will have to be appropriately designed to prevent lateral and vertical movements of any existing structures, foundations, utilities, and ground located adjacent to the excavation area. If excavation side slopes are not sufficiently braced, existing underground utilities or other structures within the 1H:1V imaginary line projecting above the bottom of the excavation may be susceptible to lateral movements. Monitoring of the retention system performance should be required during the entire time the excavation is left open.

The limits of movement for the earth retention system would be directly related to how much movement the existing site features can tolerate. We would expect that only very small deflections would be acceptable, however, this should be evaluated by the designer. We also recommend that a preconstruction survey of the area in the immediate vicinity of the excavation be performed to allow comparison of any changes in the site features due to excavation activities in front of the temporary retaining wall. We can provide assistance in developing a temporary retention system monitoring program if requested.

There are various construction methods that can be used to provide for temporary ground support during construction. Bracing using sheet piling or soldier piles and wood lagging are methods that are generally considered. Based on the presence and depth of the bedrock at this site, we anticipate soldier piles and lagging will likely be used for excavation support. We recommend bracing be installed at the time of excavation and not after the excavation is made to minimize lateral deflections. Bracing must be designed as a rigid system and constructed tightly against the retained soil.

A temporary retention system is generally designed by a contractor who specializes in this field. We recommend shoring design be let as a design/build contract, designed by a registered

Professional Engineer in the State of West Virginia. We would be available to review and comment on the contractor’s retention system design upon request.

Provided information indicates the excavation may extend into shale bedrock. It is anticipated the decomposed, severely weathered bedrock can be mechanically ripped. Deeper excavation into the bedrock will require the use of heavy-duty excavation equipment to facilitate rock break-up and removal. Jack-hammering and rock chisels may be required in utility excavations where

Responsive ■ Resourceful ■ Reliable 8 working space will be limited. Consideration should be given to the location and invert elevations of utilities planned for the project to reduce the impacts of difficult excavation. Final elevations should be chosen to reduce the amount of potential bedrock excavation.

Structural Fill Requirements

Significant amount of fill is not anticipated at this site. However if filling is proposed, the following requirements should be met. Samples of all material to be used as structural fill must be tested in the laboratory to determine its suitability and compaction characteristics.

Structural fill should meet the following material property requirements:

Fill Type 1 USCS Classification Acceptable Location for Placement

Lean clay

CL

(LL<40 & PI<22)

All locations and elevations

Medium to high plasticity lean clay 2

CL

(40<LL<50)

> 1.5 ft. below building and pavement finished soil sub-grade

Well graded granular SW or GW 3 All locations and elevations

Low Volume

Change Material 4

CL (LL<40 & PI<22) or

SW or GW 3 All locations and elevations

On-site fill soils Various

In order to be considered for reuse, fill materials should be free of organics, debris, rubble, and other deleterious material. Rock fragments must be broken down to a soil-like consistency and adhere to the compaction requirements in Section 4.2.3 Structural Fill

Placement and Compaction Requirements.

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

2. Delineation of medium to high plasticity lean clays should be performed in the field by a qualified geotechnical engineer or their representative.

3. Crushed limestone aggregate, limestone screenings, or granular material such as sand, gravel or crushed stone.

4. Low plasticity cohesive soil and well graded granular soil or Lime stabilized moderate to high plasticity soils.

Responsive ■ Resourceful ■ Reliable 9

Structural Fill Placement and Compaction Requirements

Item Description

Fill Lift Thickness

8-inches or less in loose thickness when heavy, self-propelled compaction equipment is used.

4 inches in loose thickness when hand-guided equipment

(i.e. jumping jack or plate compactor) is used.

Minimum Compaction Requirement 1, 2

Below Foundations and Slabs-on-grade

98% of the material’s maximum dry density value as determined by ASTM Standard Test Method D 698.

Moisture Content - Cohesive Soil -2% to +3% of optimum as determined by ASTM

Standard Test Method D 698

Moisture Content - Granular Material 3 Workable moisture levels

1. We recommend that each lift of cohesive and granular structural fill be tested by Terracon for moisture content and compaction prior to the placement of additional structural fill. Should the results of the in-place density tests indicate the specified moisture or compaction limits have not been met, the area represented by the test should be reworked and retested as required until the specified moisture and compaction requirements are achieved.

2. If granular material is a coarse sand or gravel, and is of a uniform size, or has a low fines content, compaction comparison to relative density may be more appropriate.

3. The gradation of a granular material affects its stability and the moisture content required for proper compaction.

Grading and Drainage

Final surrounding grades should be sloped away from the structures on all sides to prevent ponding of water. Where and if applicable, gutters and downspouts that drain water well beyond the footprint of the proposed structures are recommended. This can be accomplished through the use of splash-blocks, downspout extensions, and flexible pipes that are designed to attach to the end of the downspout. Flexible pipe should only be used if it is daylighted in such a manner that it gravity-drains collected water. Splash-blocks should also be considered below hose bibs and water spigots.

Lateral Earth Pressures for North and Western Building Walls

A reinforced concrete wall supported on drilled shafts is anticipated to be required to retain the cut on the north-west side of the proposed building. Reinforced concrete walls with unbalanced backfill levels on opposite sides should be designed for earth pressures at least equal to those indicated in the following table. Earth pressures will be influenced by structural design of the walls, conditions of wall restraint, methods of construction and/or compaction and the strength of the materials being restrained. Two wall restraint conditions are shown. Active earth pressure is commonly used for design of free-standing cantilever retaining walls and assumes wall movement. The "at-rest" condition assumes no wall movement. The recommended design lateral

Responsive ■ Resourceful ■ Reliable 10 earth pressures do not include a factor of safety and do not provide for possible hydrostatic pressure on the walls.

Earth Pressure Coefficients

Earth Pressure

Conditions

Coefficient for

Backfill Type

Equivalent Fluid

Density (pcf)

Surcharge

Pressure, p1 (psf)

Earth Pressure, p2 (psf)

Active (Ka) Granular - 0.33

Lean Clay - 0.42

(0.33)S

(0.42)S

(40)H

(50)H

At-Rest (Ko) Granular - 0.46

Lean Clay - 0.58

(0.46)S

(0.58)S

(55)H

(70)H

Passive (Kp) Granular - 3.0

Lean Clay - 2.4

Applicable conditions to the above include:

For active earth pressure, wall must rotate about base, with top lateral movements of about

0.002 H to 0.004 H, where H is wall height

For passive earth pressure to develop, wall must move horizontally to mobilize resistance

Uniform surcharge, where S is surcharge pressure

In-situ soil backfill weight a maximum of 120 pcf

Horizontal backfill, compacted between 95 and 98 percent of standard Proctor maximum dry density

Loading from heavy compaction equipment not included

No hydrostatic pressures acting on wall

No dynamic loading

No safety factor included

Ignore passive pressure in frost zone

Responsive ■ Resourceful ■ Reliable 11

Backfill placed against structures should consist of granular soils or low plasticity cohesive soils. For the granular values to be valid, the granular backfill must extend out and up from the base of the wall at an angle of at least 45 and 60 degrees from vertical for the active and passive cases, respectively.

To calculate the resistance to sliding, a value of 0.32 should be used as the ultimate coefficient of friction between the footing and the underlying soil.

To control hydrostatic pressure behind the wall we recommend that a drain be installed at the foundation wall with a collection pipe leading to a reliable discharge. If this is not possible, then combined hydrostatic and lateral earth pressures should be calculated for lean clay backfill using an equivalent fluid weighing 90 and 100 pcf for active and at-rest conditions, respectively. For granular backfill, an equivalent fluid weighing 85 and 90 pcf should be used for active and at-rest, respectively.

These pressures do not include the influence of surcharge, equipment or floor loading, which should be added. Heavy equipment should not operate within a distance closer than the exposed height of retaining walls to prevent lateral pressures more than those provided.

Drilled Shaft Foundations

The following recommendations are for supporting the proposed generator structure’s footings and slab on drilled shaft foundations.

It is recommended that each drilled shaft foundation element be at least 1.5 feet in diameter. The fill soils encountered are considered uncontrolled and are of highly variable density/consistency.

Therefore, to provide reliable end bearing support, we recommend drilled shafts be terminated with a minimum embedment length of 3 feet into bedrock.

Drilled shafts could then be proportioned based on an allowable end bearing capacity of at least

20 ksf if the above stated end bearing condition is met. Drilled shaft length may need to be adjusted (increased) to resist the lateral loads and moments acting at or near the ground surface elevation (structural loads).

The following additional construction considerations, during the drilled shaft installations, should be followed:

■ Based on the subsurface conditions encountered during the time of drilling, it is anticipated that drilled shafts will need to be constructed using temporary steel casing.

■ The actual bearing elevation at each drilled shaft location should be determined in the field during construction through inspection by an authorized representative of the geotechnical engineer.

Responsive ■ Resourceful ■ Reliable 12

■ It is recommended that no completed drilled shaft holes be left open overnight without being filled with concrete.

Soldier Pile and Lagging Retaining Wall for Southern Retaining Wall

To support the hillside in the area of the previous exploration south of the existing VA facility, a proposed 7-foot tall retaining wall with surcharge loading of 200 psf is to be constructed. We recommend a soldier pile and lagging wall due to the reported slope stability issues, and to protect against slope movement. A maximum retained soil height of 15 feet was analyzed, which corresponds to the depth of the undocumented fill encountered in Borings B-4 and B-6.

Recommendations regarding the proposed drilled shaft wall are presented in the following table:

Item Description

Maximum Retained Soil Height 15 feet

Center-to-Center Drilled Shaft Spacing 6 feet

Minimum Shaft Diameter 30 inches

Total Minimum Shaft Length 25 feet

Recommended Minimum Embedment into

Weathered Bedrock 10 feet

Structural Steel Section* W 18 x 60, Grade 50 Steel (50 ksi yield stress), encased and centered in shaft

Minimum 28-day Unconfined Compressive

Strength of Concrete (f’c) 4,000 psi

* Deflection at top of drilled shaft limited to less than about 2 inches

The rolled steel sections should be extended from the bottom of the proposed wall to the top of the wall. The wall face can then be constructed of precast concrete panels supported by the flanges of the rolled steel sections. The lagging panels can be placed behind or between the flanges of the rolled steel sections. We recommend that the steel sections be painted or galvanized for corrosion protection.

Terracon can provide assistance in preparing design drawings and specification for construction of the drilled shaft wall as an addendum to our scope of services.

Seismic Site Classification

Code Used Site Classification

International Building Code 1 C 2

1. In general accordance with the International Building Code, Seismic Site Class is based on the characteristics of the upper 100 feet of the subsurface profile.

2. The International Building Code (IBC) requires a site soil profile determination extending a depth of

100 feet for seismic site classification. The current scope requested does not include the required

100 foot soil profile determination. Borings extended to a maximum depth of approximately 50.5 feet

Responsive ■ Resourceful ■ Reliable 13 and this seismic site class definition considers that bedrock continues below the maximum depth of the subsurface exploration. Alternatively, a geophysical exploration could be utilized to potentially obtain a higher seismic site class.

5.0 GENERAL COMMENTS

Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon also should be retained to provide observation and testing services during grading, excavation, foundation construction and other earth-related construction phases of the project.

The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings, across the site, or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that further evaluation and supplemental recommendations can be provided.

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

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

APPENDIX A

FIELD EXPLORATION

TOPOGRAPHIC MAP IMAGE COURTESY OF

THE U.S. GEOLOGICAL SURVEY

QUADRANGLES INCLUDE: CATLETTSBURG,

KY (1/1/1985), HUNTINGTON, WV (1/1/1985),

BURNAUGH, KY (1/1/1989) and LAVALETTE, WV (1/1/1989).

SITE LOCATION

VA Huntington Facility Generator Project VA Medical Center

Huntington, WV

912 Morris St

Charleston, WV 25301-1425

N2165135

DIAGRAM IS FOR GENERAL LOCATION ONLY,

AND IS NOT INTENDED FOR CONSTRUCTION

PURPOSES

Project Manager:

Drawn by:

Checked by:

Approved by:

AKB

PSR

PSR

AKB

N2165135

January 2017

Project No.

File Name:

Date:

A-1

Exhibit

SITE

1”=2,000’ Scale:

EXPLORATION PLAN

912 Morris St

Charleston, WV 25301-1425

N2165135

AERIAL PHOTOGRAPHY PROVIDED BY

MICROSOFT BING MAPS

VA Huntington Facility Generator Project VA Medical Center

Huntington, WV

DIAGRAM IS FOR GENERAL LOCATION ONLY,

AND IS NOT INTENDED FOR CONSTRUCTION

PURPOSES

Project Manager:

Drawn by:

Checked by:

Approved by:

AKB

PSR

PSR

AKB

N2165135

January 2017

Scale:

Project No.

File Name:

Date:

AS SHOWN

A-2

Exhibit

Exhibit A-3

Field Exploration Description

The subsurface exploration consisted of drilling and sampling six (6) test borings at the site, designated B-7 through B-12, to depths ranging from 31.5 to 50.5 feet below the existing surface grade. These borings are in addition to the six (6) borings performed as part of our original

Geotechnical Report, dated August 4, 2016 (Borings B-1 through B-6). The as-drilled boring locations are depicted in Exhibit A-2: Boring Location Plan. The borings were staked in the field by Terracon. The ground surface elevation at the test boring locations have been estimated from

Google Earth. The location and elevation of the borings should be considered accurate only to the degree implied by the means and method to define them.

The test borings were drilled with a track-mounted rotary drill rig. Hollow stem augers were used to advance the boreholes and the split-barrel sampling procedure was used to collect samples in the advance of the augers. In the split-barrel sampling procedure, the number of blows required to advance a standard 2-inch O.D. split-barrel sampler the last 12 inches of the typical total 18-inch penetration by means of a 140-pound C.M.E. auto-hammer with a free fall of 30 inches, is the standard penetration resistance value (SPT-N). This value is used to estimate the in-situ relative density of granular soils and consistency of cohesive soils.

An automatic SPT hammer was used to advance the split-barrel sampler in the borings performed on this site. A greater efficiency is typically achieved with the automatic hammer compared to the conventional safety hammer operated with a cathead and rope. Published correlations between the SPT values and soil properties are based on the lower efficiency cathead and rope method.

This higher efficiency affects the standard penetration resistance blow count (N) value by increasing the penetration per hammer blow over what would be obtained using the cathead and rope method.

Rock coring was performed using a NQ-size double tube-swivel core barrel. Percent recovery and rock quality designation (RQD) were calculated for the core samples and are noted at their depths of occurrence on the boring logs. RQD is the percent of total length cored consisting only of rock pieces at least 4 inches or more in length and is a measure of the integrity of the rock mass in-situ.

The spilt-barrel samples were sealed in watertight glass jars upon sample extraction. All samples were returned to the laboratory for testing and classification.

Field logs of the borings were prepared by the drill crew. The logs included visual classifications of the materials encountered during drilling as well as the driller’s interpretation of the subsurface conditions between samples. The final boring logs are included with this report represent the engineer's interpretation of the field logs and include modifications based on laboratory observation and tests of the samples.

3-3-3 N=6

3-3-3 N=6

2-2-2 N=4

20-11-11 N=22

49-50/4"

16-18-18 N=36

18-38-49 N=87

43-50/3"

7.5

FILL - SANDY LEAN CLAY WITH ROCK FRAGMENTS

(CL), micaceous, light brown to dark brown, orangish-brown and trace black

SANDY SHALE, micaceous, brown, laminated bedding, residual soil, extremely weak

862.5

G R

A P

H

IC

L O

G

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

T

G

E O

S M

A R

T L

O G

-N O

W E

LL

N

5_

H U

N T

IN

G

T O

N V

A M

E D

IC

A

L C

E N

T E

R A

LL

L

O G

S .G

P J

T E

R R

A C

O N

.G D

T

/4 /1

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

LOCATION

Latitude: 38.376188° Longitude: -82.516505°

See Exhibit A-2

LA

B

O R

A T

O R

Y T

O R

V A

N E

/H P ps f)

W A

T E

R C

O N

T E

N T

LL-PL-PI

ATTERBERG

LIMITS

ELEVATION (Ft.)

Surface Elev.: 870 (Ft.)

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R E

C O

V E

R Y

In

R Q

D

Huntington, West Virginia

SITE:

Advancement Method:

3.25" Hollow Stem Auger

Abandonment Method:

Boring backfilled with soil cuttings upon completion.

Notes:

Project No.: N2165135

Drill Rig: Track

Boring Started: 7/6/2016

BORING LOG NO. B-1

Guidon DesignCLIENT:

Indianapolis, Indiana

Driller: L. Slate

Boring Completed: 7/6/2016

Exhibit: A-4

See Exhibit A-3 for description of field procedures.

See Appendix B for description of laboratory procedures and additional data (if any).

See Appendix C for explanation of symbols and abbreviations.

PROJECT: Huntington VA Generator Facility Project

912 Morris St Charleston, WV

No free water observed

WATER LEVEL OBSERVATIONS

50/4"

50/1"

28.5

32.5

35.0

46.0

SANDY SHALE, micaceous, brown, laminated bedding, residual soil, extremely weak (continued)

SHALE, trace sand, micaceous, gray to dark medium gray, laminated bedding, highly to completely weathered, extremely weak

SANDSTONE, micaceous, light gray, fine-grained, close fracture spacing, thin bedding, slightly weathered to unweathered, weak rock

CLAYSTONE, gray to reddish-gray, extremely close fracture spacing, very thin bedding, highly to completely weathered, extremely weak to very weak

SANDSTONE, micaceous, light gray, fine-grained, close fracture spacing, thin bedding, slightly weathered to unweathered, medium strong

841.5

837.5

G R

A P

H

IC

L O

G

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

O

S M

A R

T L

O G

-N O

W E

LL

N

5_

H U

N T

IN

G

T O

N V

A M

E D

IC

A

L C

E N

T E

R A

LL

L

O G

S .G

P J

T E

R R

A C

O N

.G D

T

/4 /1

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

LOCATION

Latitude: 38.376188° Longitude: -82.516505°

See Exhibit A-2

LA

B

O R

A T

O R

Y T

O R

V A

N E

/H P ps f)

W A

T E

R C

O N

T E

N T

LL-PL-PI

ATTERBERG

LIMITS

ELEVATION (Ft.)

Surface Elev.: 870 (Ft.)

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R E

C O

V E

R Y

In

R Q

D

Huntington, West Virginia

SITE:

Advancement Method:

3.25" Hollow Stem Auger

Abandonment Method:

Boring backfilled with soil cuttings upon completion.

Notes:

Project No.: N2165135

Drill Rig: Track

Boring Started: 7/6/2016

BORING LOG NO. B-1

Guidon DesignCLIENT:

Indianapolis, Indiana

Driller: L. Slate

Boring Completed: 7/6/2016

Exhibit: A-4

See Exhibit A-3 for description of field procedures.

See Appendix B for description of laboratory procedures and additional data (if any).

See Appendix C for explanation of symbols and abbreviations.

PROJECT: Huntington VA Generator Facility Project

912 Morris St Charleston, WV

52.0

55.0

SANDSTONE, micaceous, light gray, fine-grained, close fracture spacing, thin bedding, slightly weathered to unweathered, medium strong (continued)

CLAYSTONE, gray to reddish-gray, extremely close fracture spacing, very thin bedding, highly to completely weathered, weak rock

Boring Terminated at 55 Feet

52 13

G R

A P

H

IC

L O

G

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

O

S M

A R

T L

O G

-N O

W E

LL

N

5_

H U

N T

IN

G

T O

N V

A M

E D

IC

A

L C

E N

T E

R A

LL

L

O G

S .G

P J

T E

R R

A C

O N

.G D

T

/4 /1

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

LOCATION

Latitude: 38.376188° Longitude: -82.516505°

See Exhibit A-2

LA

B

O R

A T

O R

Y T

O R

V A

N E

/H P ps f)

W A

T E

R C

O N

T E

N T

LL-PL-PI

ATTERBERG

LIMITS

ELEVATION (Ft.)

Surface Elev.: 870 (Ft.)

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R E

C O

V E

R Y

In

R Q

D

Huntington, West Virginia

SITE:

Advancement Method:

3.25" Hollow Stem Auger

Abandonment Method:

Boring backfilled with soil cuttings upon completion.

Notes:

Project No.: N2165135

Drill Rig: Track

Boring Started: 7/6/2016

BORING LOG NO. B-1

Guidon DesignCLIENT:

Indianapolis, Indiana

Driller: L. Slate

Boring Completed: 7/6/2016

Exhibit: A-4

See Exhibit A-3 for description of field procedures.

See Appendix B for description of laboratory procedures and additional data (if any).

See Appendix C for explanation of symbols and abbreviations.

PROJECT: Huntington VA Generator Facility Project

912 Morris St Charleston, WV

2-3-4 N=7

3-4-4 N=8

5-6-8 N=14

3-4-6 N=10

3-3-6 N=9

10-50/4"

50/5"

38-50/4"

13.0

25.0

FILL - SANDY LEAN CLAY WITH ROCK FRAGMENTS

(CL), trace silt, micaceous, light brown to orangish-brown, trace black

SANDY SHALE, micaceous, light brown, laminated bedding, completely weathered to residual soil, extremely weak

G R

A P

H

IC

L O

G

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

O

S M

A R

T L

O G

-N O

W E

LL

N

5_

H U

N T

IN

G

T O

N V

A M

E D

IC

A

L C

E N

T E

R A

LL

L

O G

S .G

P J

T E

R R

A C

O N

.G D

T

/4 /1

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

LOCATION

Latitude: 38.376203° Longitude: -82.516386°

See Exhibit A-2

LA

B

O R

A T

O R

Y T

O R

V A

N E

/H P ps f)

W A

T E

R C

O N

T E

N T

LL-PL-PI

ATTERBERG

LIMITS

ELEVATION (Ft.)

Surface Elev.: 870 (Ft.)

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R E

C O

V E

R Y

In

R Q

D

Huntington, West Virginia

SITE:

Advancement Method:

3.25" Hollow Stem Auger

Abandonment Method:

Boring backfilled with soil cuttings upon completion.

Notes:

Project No.: N2165135

Drill Rig: Track

Boring Started: 7/7/2016

BORING LOG NO. B-2

Guidon DesignCLIENT:

Indianapolis, Indiana

Driller: L. Slate

Boring Completed: 7/7/2016

Exhibit: A-5

See Exhibit A-3 for description of field procedures.

See Appendix B for description of laboratory procedures and additional data (if any).

See Appendix C for explanation of symbols and abbreviations.

PROJECT: Huntington VA Generator Facility Project

912 Morris St Charleston, WV

32.0

35.0

45.0

CLAYSTONE, with sand, micaceous, light brown and gray with iron-staining, very close fracture spacing, very thin bedding, highly weathered, extremely weak

SANDSTONE, micaceous, light gray with iron-staining, close fracture spacing, thin bedding, slightly weathered to unweathered, medium strong

CLAYSTONE, dark medium gray, very close fracture spacing, very thin bedding, highly weathered to residual soil, extremely weak

Boring Terminated at 45 Feet

G R

A P

H

IC

L O

G

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

O

S M

A R

T L

O G

-N O

W E

LL

N

5_

H U

N T

IN

G

T O

N V

A M

E D

IC

A

L C

E N

T E

R A

LL

L

O G

S .G

P J

T E

R R

A C

O N

.G D

T

/4 /1

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

LOCATION

Latitude: 38.376203° Longitude: -82.516386°

See Exhibit A-2

LA

B

O R

A T

O R

Y T

O R

V A

N E

/H P ps f)

W A

T E

R C

O N

T E

N T

LL-PL-PI

ATTERBERG

LIMITS

ELEVATION (Ft.)

Surface Elev.: 870 (Ft.)

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R E

C O

V E

R Y

In

R Q

D

Huntington, West Virginia

SITE:

Advancement Method:

3.25" Hollow Stem Auger

Abandonment Method:

Boring backfilled with soil cuttings upon completion.

Notes:

Project No.: N2165135

Drill Rig: Track

Boring Started: 7/7/2016

BORING LOG NO. B-2

Guidon DesignCLIENT:

Indianapolis, Indiana

Driller: L. Slate

Boring Completed: 7/7/2016

Exhibit: A-5

See Exhibit A-3 for description of field procedures.

See Appendix B for description of laboratory procedures and additional data (if any).

See Appendix C for explanation of symbols and abbreviations.

PROJECT: Huntington VA Generator Facility Project

912 Morris St Charleston, WV

2-3-3 N=6

6-6-6 N=12

4-4-4 N=8

2-3-3 N=6

4-4-4 N=8

16-25-24 N=49

50/4"

36-50/4"

13.5

25.0

FILL - SANDY LEAN…