Geotechnical Report 04-20-0534-IDC DLC Facility-Final 9-14-22.pdf

TRIAD Listens, Designs & Delivers

REPORT OF

GEOTECHNICAL EXPLORATION

INSTRUCTIONAL DESIGN CENTER (IDC) / DISTANCE

LEARNING CENTER (DLC) FACILITY

HARPERS FERRY, WEST VIRGINIA

TRIAD PROJECT NO. 04-20-0534

PREPARED FOR:

MICHAEL BAKER INTERNATIONAL

1501 LYNDON B JOHNSON FWY, SUITE 650

DALLAS, TX 75234

PREPARED BY:

10541 TEAYS VALLEY ROAD

SCOTT DEPOT, WEST VIRGINIA 25560

WWW.TRIADENG.COM

SEPTEMBER 14, 2022

September 14, 2022

Mr. Jason Tackett Michael Baker International 1501 Lyndon B Johnson Fwy Suite 650.

Dallas, TX 75234

RE: Report of Geotechnical Exploration Instructional Design Center (IDC)/Distance Learning Center (DLC) Facility Harpers Ferry, WV Triad Proposal No. 04-20-0534

Dear Mr. Tackett:

In accordance with your request, we have completed a geotechnical exploration for the proposed Instructional Design Center (IDC) / Distance Learning Center (DLC) Facility project located in Harpers Ferry, West Virginia. Authorization to proceed with this project was provided via receipt of the Subconsultant Agreement dated November 30, 2020. The subsurface exploration was performed to evaluate the subsurface conditions encountered at the proposed facility for the limited purposes of preparing design and construction recommendations for geotechnical aspects of the project. It is emphasized that subsurface conditions may vary dramatically between borings, and Triad makes no representations as to subsurface conditions other than those encountered at the specific test boring locations.

This report has been prepared for the exclusive use of Michael Baker International for specific application to the evaluation of the proposed IDC / DLC Facility project located in Harpers Ferry, West Virginia. Triad’s responsibilities and liabilities are limited to our Client and apply only to their use of our report for the purposes described above. To observe compliance with design concepts and specifications, and to facilitate design changes in the event that subsurface conditions differ from those anticipated prior to construction, it is recommended that Triad be retained to provide continuous engineering and testing services during the earthwork and foundation construction phases of the work.

We appreciate the opportunity to assist you on this project and trust this report satisfies your needs at this time. Please feel free to contact us if you have questions concerning this report, or if we can provide further assistance.

Sincerely, TRIAD ENGINEERING, INC.

John J. Haynes, P.E.

Geotechnical Practice Leader

David W. Hooper, P.E.

Principal Engineer

TABLE OF CONTENTS

Item Page

FOREWORD

SITE AND PROJECT DESCRIPTION

GEOLOGIC SETTING

SUBSURFACE EXPLORATION

SUBSURFACE CONDITIONS

Soil Conditions Groundwater

LABORATORY TESTING

DISCUSSION

DESIGN RECOMMENDATIONS

Micropile Foundation Recommendations Lateral Loaded Pile Recommendations Floor Slab Recommendations Pavement Considerations Seismic Considerations

CONSTRUCTION RECOMMENDATIONS

Site Preparation Site Excavations Structural Fill Material Fill Placement and Compaction Groundwater Quality Assurance and Control

APPENDICES

Appendix A - Illustrations Appendix B - Field Exploration Appendix C - Laboratory Testing Appendix D - Corrosivity Testing Appendix E - Seismic Information Appendix F – Settlement Analyses Appendix G – Frost Depth Analysis

REPORT OF GEOTECHNICAL EXPLORATION

Instructional Design Center (IDC)/Distance Learning Center (DLC) Facility

Harpers Ferry, West Virginia Triad Project No. 04-20-0534

FOREWORD

This report has been prepared for the exclusive use of Michael Baker International for specific application to the evaluation of the proposed Instructional Design Center (IDC) / Distance Learning Center (DLC) Facility project located in Harpers Ferry, West Virginia.

The work has been performed in accordance with generally accepted geotechnical engineering practices. No other warranty, expressed or implied, is made.

This report should not be used for estimation of construction quantities and/or costs, and contractors should conduct their own investigation of site conditions for these purposes. Please note that Triad is not responsible for any claims, damages or liability associated with any other party’s interpretation of the data or re-use of these data or engineering analyses without the express written authorization of Triad. Additionally, this report must be read in its entirety. Individual sections of this report may cause the reader to draw incorrect conclusions if considered in isolation from each other.

The conclusions and recommendations contained in this report are based, in part, upon our field observations and data obtained from the test borings at the site. The nature and extent of variations may not become evident until construction. If variations then appear evident, it may be necessary to re-evaluate the recommendations presented herein. Similarly, in the event that any changes in the nature, design, or location of the facilities are planned, the conclusions and recommendations contained herein shall not be considered valid unless the changes are reviewed, and the conclusions are modified or verified in writing by Triad.

It is recommended that we be provided the opportunity to review the final grading plan, overall foundation design, and specifications so that earthwork and foundation recommendations may be properly interpreted and implemented.

SITE AND PROJECT DESCRIPTION

It is our understanding that a new facility within the US Customs and Border Protection (CBP) Advanced Training Facility (ATC) is being proposed. The general location of the proposed project is shown on Figure No. A-1 in Appendix A of this report. The new structure will house the Instructional Design Center (IDC) / Distance Learning Center (DLC). The facility will provide offices, staff workstations, other learning areas, conference rooms and accommodate 200 parking spaces. The facility is proposed to have an approximate footprint of 15,672 square feet and the parking lot will be approximately 7,918 square feet. It is our understanding that the finished floor elevation is planned to be 407.87 feet, which ranges from approximately 0.5 to 5 feet above the existing ground elevation across the building footprint. Specific details such as site

Michael Baker International September 14, 2021 Triad Project No. 04-20-0534 Page 2 grading, final building location, number of stories, and final overall footprint, as well as proposed foundation loading were not available at the time that this report was prepared.

GEOLOGIC SETTING

The site is located within the Blue Ridge physiographic province, along the eastern edge of the Great Valley. While the surficial topography of the Great Valley is relatively flat, the bedrock beneath is heavily folded and faulted – more so than the Valley and Ridge province to the west. The bedrock underlying the project sites is part of the eastern edge of the eastern limb of the Massanutten Synclinorium, which spans the width of the Great Valley. The soft shales and carbonate rocks that underly the Great Valley are less resistant to weathering and erosion, resulting in the wide, flat expanse observed to the west of the Blue Ridge Anticlinorium. The western portion of the site is immediately underlain by the Tomstown Formation while the eastern portion of the site is underlain by the Red Run Member, both of the Early Cambrian geologic period. The Tomstown Formation contains thick-bedded dolomite, with some siliceous limestone and chert. The Red Run Member contains gray sandstone and sandy dolomitic limestone.

The rock formations that underlies the site, in particular the Tomston are solution-prone, calcareous and can weathers differentially to produce a pinnacled top of rock profile.

The degree of weathering or solutioning within the bedrock is controlled by joint orientation and frequency. Where joints intersect or are highly fractured, subsequent solutioning is intensified creating low areas and seams that are generally filled with residual clay soils. Conversely, more competent high areas represent slightly to non-weathered rock units that are often coarse-grained and only slightly solution prone.

West Virginia Geological and Economic Survey Coal Bed Mapping was reviewed, and no coal mining activity has been mapped in the site vicinity, due to the fact that coal seams are not present in the stratigraphic column in the region of the project site.

Development in Karst Terrain

Karst terrain, such as that which underlies the site, is characterized by caves, internal drainage, lack of surface streams, and topographic features such as sinkholes. These features are the result of the dissolution of soluble bedrock, such as limestone or dolomite, by groundwater. As groundwater enters fractures and bedding planes in soluble carbonate bedrock, it slowly (over millions of years) dissolves the rock and enlarges the fractures. This results in the formation of solutioning channels or underground streams or ravines. Sinkholes are created by the subsidence of unconsolidated materials (soils) into underlying voids such as solutioning channels or caves. Usually, subsidence occurs slowly and steadily over geologic time. Many sinkholes, however, are caused by a sudden collapse of a solutioning cave when the roof of the cave becomes too thin to support the overburden materials. Sinkholes recently created by such a collapse can usually be identified by the presence of freshly broken rock outcrops around the rim or throat of the sinkhole.

Triad Project No. 04-20-0534 Page 3

It is important to note that there are certain risks that exists when developing in these karst areas. These risks can include groundwater contamination and flooding due to the unpredictable groundwater flow paths within the bedrock, but primarily subsidence.

In these instances, water is the primary cause of the problem. Alterations in the ground surface, particularly in cut areas, during construction can impact the natural drainage within the site, and it is common to have small solutioning features develop in these areas as a result of construction. Also, normal blasting required to remove hard rock can create micro-fractures within the bedrock that will allow greater surface water infiltration into areas that may normally not receive water and, in turn, disturb old solutioning features and/or possibly create new solutioning features. Although these features are not typically enormous (building size) in this general geographic area, they can result in some minor delays and unanticipated costs for remediation during construction.

As mentioned, water is the primary cause of sinkhole development. Therefore, during construction, the contractor should grade the site such that surface water is directed to the temporary sediment traps and/or SWM facilities. This could be achieved by overall site grading as well as diversion ditches when necessary. In order to limit ponding within utility trenches, we recommend that trenches be backfilled and sealed at the end of each day. After concrete placement for foundations, the foundations should be backfilled as soon as practically possible in order to prevent ponding of water adjacent to completed foundations. In addition, areas around completed foundations should be graded such that surface water will be diverted away and not allowed to pond.

SUBSURFACE EXPLORATION

The subsurface exploration included a total of ten (10) test borings (B-1 through B-10) and two (2) auger probes (AP-1 and AP-2) extended to refusal on apparent bedrock.

Borings B-1 through B-6 as well as AP-1 and AP-2 were drilled withing the proposed building footprint. The remaining borings were drilled around the proposed building and in proposed parking areas. The boring locations are shown on the Boring Location Plan provided as Figure No. A-2 in Appendix A of this report. The locations of the test borings were determined by our discussions with the design team and established in the field by Triad personnel using existing site features and the preliminary site plan that was provided. Boring elevations were estimated based upon topographic survey data provided by you.

SPT samples were obtained from the borings and were logged in the field and then placed in air-tight glass jars. Upon completion of the drilling, borings were backfilled with auger cuttings, and the soil samples were delivered to our materials testing laboratory and were reviewed by our geotechnical engineer.

Triad Project No. 04-20-0534 Page 4

SUBSURFACE CONDITIONS

Soil Conditions

Detailed information and descriptions of the materials and groundwater levels encountered in the borings are contained in Appendix B on the Test Boring Logs.

Please refer to Figure Nos. B-1 and B-2, also in Appendix B, for additional information regarding the material descriptions and terminology utilized. Subsurface conditions encountered at the boring locations are generalized in the following table.

Stratum Material Type(s) Approximate Depth to

Bottom of Stratum Material

Density/ Hardness

Stratum 1 Fill: Sandy Clay, Gravelly Clay, and Clayey Gravel

Encountered in each boring and extending to depths ranging from 2.0 to 6.0 feet in each boring.

Medium Dense to Dense and Medium

Stiff to Very Stiff

Stratum 2 Cohesive Soil: Lean

Clay, Fat Clay, Sandy Clay, and Gravelly Clay

Encountered below the fill and extending to depths ranging from 15 to 16 feet in borings 1, 5, 6, 9 and 10.

Medium Stiff to Very Stiff

Stratum 3 Bedrock: Limestone

Encountered at depths ranging from 2.0 to 14.0 feet and extending to termination depths in each boring.

Medium hard to hard.

Slightly to moderately weathered.

The stratification indicated in the above table is a general description of conditions observed in the test borings. Actual transitions between strata could be gradual. For more specific details regarding the subsurface conditions, refer to the test boring logs in Appendix B of this report. It is emphasized that the lines shown on the logs are estimates of the changes in material. Actual changes may vary from those indicated on the logs, and the subsurface conditions across the site may differ from those depicted on the logs.

Groundwater

Groundwater levels were checked both during and after drilling operations. Each boring was dry during drilling. Water was observed immediately following drilling completion in borings B-1, B-3, B-4, and B-6 at depths ranging from 4.0 to 9.6 feet below the existing ground surface. It is noted that the introduction of water was necessary to core bedrock within these borings and the observed water is likely to be remnants of the water introduced during rock coring and is unlikely to be representative of groundwater levels.

Water was not observed in any boring that was not subject to rock coring.

It is emphasized that fluctuations in true groundwater levels can occur due to variations in seasonal, climatic, and environmental conditions which may not have been evident at the time of the field exploration. Consequently, groundwater levels can vary significantly from those recorded at the time measurements were taken.

Triad Project No. 04-20-0534 Page 5

LABORATORY TESTING

Laboratory tests were performed on selected soil samples to aid in classification and provide a basis for estimating their engineering properties. The laboratory tests were performed in accordance with ASTM standard test methods. Individual test results are shown on the test boring logs in Appendix B, and detailed results are contained in Appendix C. The test results are summarized in the following table.

EXISTING FILL – STRATUM 1

TEST TYPE TEST RESULTS

Moisture Content 8.4 to 21.7 and 33.8 %

Atterberg Limits Liquid Limit Plasticity Index

30 to 84 13 to 54

Percent Passing No. 200 Sieve 13 to 93 %

USCS Classification GC, CL, and CH

Standard Proctor Max Dry Density Optimum Moisture

110.6 pcf

16.1 %

California Bearing Ratio (for 0.1 inch of penetration at 95% density)

6.4 %

NATIVE SOIL – STRATUM 2

Moisture Content 4.9 to 37.1 %

Atterberg Limits Liquid Limit Plasticity Index

79 to 85 51 to 54

Percent Passing No. 200 Sieve 94 to 99 %

USCS Classification CH

Chemical analysis for use in determining corrosivity of the site soils was performed by Pace Analytical for Triad. Resistivity testing was performed by Triad’s laboratory. The results of these tests are summarized below and included in Appendix D.

CORROSIVITY TESTING

pH at 25 Degrees C 7.8 to 7.9

Chloride Content Not Detected and 22 mg/kg

Sulfate Content 126 to 261 mg/kg

Minimum Soil Resistivity 1,687 to 2,286 ohm-cm

Site Corrosivity Corrosive (1)

(1) Corrosivity based on low resistivity value of less than 2,000 ohm-cm

Triad Project No. 04-20-0534 Page 6

DISCUSSION

Based on provided information, the finished floor of the structure will be approximately 1-foot above the ground level on the outside of the building. The finished floor elevation is proposed to be 407.87 feet and the ground surface outside of the building is planned to be approximately 406.87 feet. The ground surface elevations of the borings drilled within the proposed footprint ranged from approximately 403 feet to 407.5 feet, indicating that earthwork ranging from approximately 4 feet of fill to less than 1 foot of cut will be required to obtain design grade.

Existing fill material was encountered in each boring to depths ranging from 2 to 6 feet below the existing ground surface. Native soil was encountered beneath the fill in borings B-1, B-5, B-6, B-9, and B-10. Bedrock was encountered beneath the fill in borings B-2 through B-4, B-7, and B-8. There was no information provided concerning the construction methods or compaction testing utilized during placement of the existing fill. However, we understand that the fill encountered in the test borings was likely placed as a part of the original site development. Relative stiffness and relative densities of the encountered fill ranged from medium stiff to very stiff for cohesive material and medium dense to dense for granular material. The SPT N-values in the encountered fill ranged from 6 to 43 blows per foot (bpf). Additionally, highly plastic clay was encountered in several borings across the site, which is common within the geologic area.

Conventional shallow foundations can be used for support of the proposed facility.

Total settlement of 3 8 to 3 4 inches has been estimated as shown in Appendix F. As bedrock is anticipated to be at foundation bearing level at other areas of the site, this total settlement is also estimated to be differential settlement. Additionally, we must note that constructing foundations and or structures on or above existing fill carries some risk that unsuitable or deleterious material exists within the fill that was not encountered during our exploration and may also not be encountered during construction. Consequently, there is some risk that larger than expected settlement or earth movement may occur if shallow foundations bearing on this fill material is utilized.

Shallow foundations are expected to bear near approximate elevation 404.3 feet for exterior foundations with interior foundations bearing higher at approximately 1.5 feet below finished slab. Highly plastic clays if encountered are not suitable for direct foundation bearing due to the shrink/swell potential of this type of soil. These soils should be removed if encountered directly below the foundation. Additionally, limestone bedrock was encountered at approximate elevations ranging from 391 to 403.5 in borings B-1 to B-6 and AP-1 to AP-2 which corresponds to depths below bearing elevation of approximately 1 foot to 14 feet. As such, in areas where bedrock is present at the proposed bearing elevation or where highly plastic clay is encountered at bearing elevation, the foundation excavation should be over-excavated 2 feet and replaced with new structural fill in accordance with our “Construction Recommendations” section.

Foundations can then be constructed at the specified bearing elevation on the new structural fill.

Triad Project No. 04-20-0534 Page 7

Shallow foundations provided limited protection against sinkholes resulting from karst conditions. We understand that the owner has selected a higher level of protection for the structure against sinkholes with the use of micropile foundations. Micropiles extend the foundations through the existing fill and or native soil and into competent bedrock developing their capacity from a skin resistance bond with the bedrock. During the installation of the micropiles the drilling can be used to further assess the karst nature of the rock. Micropiles are the selected deep foundation option as they have the ability to be installed by drilling methods to accommodate pinnacled rock surface and to be advanced through solution features.

In addition to the building foundations, the owner has elected to decrease the risk to the structure due ot karst conditions by having the slab-on-grade designed to span a sinkhole opening. Although this technique does decrease the risk to the structure, prediction of the size of a sinkhole opening is impossible to predict based on the available information.

The clayey soils encountered on the site are expected to be sensitive to moisture fluctuations. These materials can become unstable under construction traffic traversing the site, especially by rubber tired equipment. Therefore, site grading should be performed during drier months, if possible.

DESIGN RECOMMENDATIONS

Micropile Foundation Recommendations

Micropiles are to be extended to bear within competent bedrock. Due to the Karst nature of the bedrock, a minimum overall bond length within rock of 10 feet, including a minimum intact rock bonded length of 6 feet, is required for each micropile. Due to the nature of their construction when compared with conventional drilled shafts or driven steel piles, micropiles are useful where the depth to bedrock ranges greatly and within Karst areas where voids may be encountered within bedrock. It is emphasized that it is possible that bedrock is deeper than 14 feet. Therefore, some contingency for the depth to rock should be considered by the designer.

Micropiles should bear within competent bedrock. We recommend that a maximum allowable bond resistance of 80 psi between the rock and grout materials be utilized for design of the micropiles. Based on our past experience, working capacities of 400 kips (200 tons) can be achieved with properly designed micro-piles, though the necessary capacity for the relatively small building is anticipated to be significantly lower. The micropiles should be designed with a factor of safety of 2.0 for axial capacity. We recommend that the micro-piles extend at least 10 feet into or to that distance determined by the designer/installer to develop the necessary load capacity. If individual voids in excess of 4 inches are encountered while drilling for the bond zone, drilling should proceed to obtain the full bond zone beneath those void. No other redundancy is required to accommodate the karst conditions. Casing should be provided in accordance with the project design and construction specifications to depths of the top of the competent zone of bedrock. Micro-pile spacing should not be less than 36 inches

Triad Project No. 04-20-0534 Page 8 or 2.5 times the micropile diameter, whichever is greater. Individual or group micro-pile settlement should be insignificant for deep foundations bearing in bedrock. For deep foundations constructed to bear in bedrock, a reduction in capacity for pile group action is unnecessary. Due to the potentially corrosivity of the site soils, we recommend the micropile out casing be designed for a potential loss of 1/16” due to corrosion.

Pile caps should be constructed to bear at a minimum depth of 30 inches below the final exterior grade in order to provide adequate frost protection. Calculations for frost depth determination are provided in Appendix G.

Research and field tests have shown that frictional resistance between soil and piles can be activated with movements on the order of 0.10 to 0.25 inches. Considering the loading from approximately 4 feet of fill, the dead load of the slab and the floor live load, we would not anticipate measurable settlement to occur that would impact the piles. Fill placement is expected to take place prior to pile installation, and any minor settlement associated with that is anticipated to be primarily elastic/immediate in nature for the generally stiff, over-consolidated site soils, and thus would not induce appreciable relative movement of soil to pile subsequent to pile installation. Therefore the design of the micropiles to accommodate negative skin friction is not necessary.

Micropile design and installation is a specialized product/process. We recommend that you engage a qualified and experienced specialty contractor to evaluate the conditions and develop an appropriate micropile design. It is imperative that the installer perform their own evaluation of the site suitability for micro-piles. It will also be necessary for the structural engineer to provide load requirements for the foundations and tolerable settlement criteria for the structure. After their evaluation is complete, specifications for micro-pile installation should be developed by the installer. When the specifications are complete, they should be reviewed by the geotechnical engineer. A total of one (1) verification load test shall be performed prior to installation of production piling and 3 proof tests on production piles should be performed throughout the construction of the foundations.

Lateral Loaded Pile Recommendations

The lateral resistance of the vertical piles for the structure should be determined through the use of LPILE analyses based on the vertical, shear and moment loads applied to the head of the pile. Soil and rock parameters for lateral load analysis of piles using the LPILE computer program are tabulated below.

Triad Project No. 04-20-0534 Page 9

Material Type

Material Modeled

As

Moist Unit

Weight γ

(pcf)

Saturate d Unit Weight γ (pcf)

Cohesion c

(psf)

Strain Factor

E50

Soil Modulus k (lbs/in3)

Initial Modulus of Rock Mass

(lbs/in2) krm

RQD

Unconfined Compressive

Strength (psi)

Stiff Clay Above Water

Stiff Clay w/o Free Water

(Reese) 120 125 150 0.005 N/A N/A N/A N/A N/A

Clay Below Water

Stiff Clay with Free Water (Matlock)

120 125 150 0.005 500 N/A N/A N/A N/A

Weak Bedrock

Weak Rock (Reese)

140 145 N/A N/A N/A 20,000 0.00009 20 200

Bedrock Strong Rock

140 145 N/A N/A N/A N/A N/A N/A 3,000

Floor Slab Recommendations

Based on the information provided and the recommendations in this report, it is anticipated that proposed slabs will bear on existing fill or new fill. At the request of the owner, the slab will be designed to span potential sinkholes due to the karst conditions.

We recommend that the site be stripped, cut to finished grade and the subgrade be proof-rolled. If bedrock is encountered at floor slab subgrade level in any areas of the building, it is to be undercut a minimum of 12 inches and replaced with compacted structural fill. After completion of proof-rolling and repair of soft soil areas (if any), the top 12 inches of slab subgrade in areas where the subgrade is soil should be compacted to the fill criteria presented in this report. The recommendations in the “Construction Recommendations” section of this report should be strictly followed to reduce the probability of subgrade failure. These materials should provide adequate support for slab-on-grade construction using a modulus of subgrade reaction of 90 pounds per cubic inch, provided that the recommendations presented herein are utilized. A minimum four-inch layer of crushed stone such as ASTM No. 57 coarse aggregate should be placed under the slab-on-grade to serve as a capillary water barrier and a leveling surface. A six-mil thick polyethylene vapor barrier should be placed between the aggregate and concrete slab

Pavement Considerations

Based on the information provided, it is anticipated that the proposed pavement areas will be constructed over existing fill or new fill depending on the proposed grading plan, which was not available at the time of this report. The recommendations in the “Construction Recommendations” section of this report should be strictly followed to reduce the probability of subgrade failure. Where additional pavement is to be placed, it is important that both the base stone and pavement be placed immediately after final soil subgrade approval has been obtained due to the potential for subgrade softening from adverse weather conditions. In addition, heavy construction traffic should be

Triad Project No. 04-20-0534 Page 10 limited from traveling across approved final subgrade areas in order to help maintain a stable subgrade prior to pavement construction. The frost depth for pavement design of 36 inches is recommended.

Pavement, aggregate material, and placement procedures should be in accordance with West Virginia Department of Transportation Division of Highways Standard Specifications Roads and Bridges, latest edition. The subgrade should be graded such that water does not become trapped or ponded on or beneath the pavement system.

Should adequate drainage not be obtained by crowning the subgrade, an appropriate underdrain system should be designed and constructed to remove water from the subgrade/subbase system.

Soil samples were collected during the subsurface exploration for preliminary pavement design purposes. California Bearing Ratio (CBR) tests were completed on these samples. The samples provide representative CBR values for the sampled materials.

Based on the testing as well as our experience with similar soil and site conditions, we recommend using a CBR value for the existing fill material of 6.0, as long as the subgrade is prepared as per the recommendations presented in this report.

Additionally, we recommend that additional CBR tests be performed on proposed new fill materials that are planned to be used to establish the subgrade. The pavement should then be designed using the resulting CBR values for the specific subgrade materials. The subgrade should be graded such that water does not become ponded or entrapped beneath the pavement system. We recommend that a heavier asphalt section be designed for use in areas which will receive heavy truck traffic. Rigid pavement is recommended for dumpster enclosures.

Seismic Considerations

The site soils were evaluated and classified according to the 2015 International Building Code Section 1613 - Earthquake Loads - Site Ground Motion. This building code establishes the criteria for project site evaluation. Section 1613.5.2 and Table 1613.5.2, defines the parameters for determining the seismic site class. The seismic site class may be determined by calculating an N value of subsurface materials to a depth of 100 feet. For the determination, the N values recorded in test borings are used for overburden soil, and then, typically, materials below the depth that auger refusal or hard rock is encountered (to a depth of 100 feet) are assigned an N-value of 100. Based on the results of the test borings, the site has an N value of 76. Using the calculated N value along with knowledge of the site geologic setting, the seismic site class and additional seismic information is as follows:

Seismic Site Class C

Soil Profile Name Very Dense Soil and Soft Rock

Site Coefficient Fa 1.2

Site Coefficient Fv 1.7

Mapped Spectral Acceleration for Short Periods Ss 0.128

Mapped Spectral Acceleration for Short Periods S1 0.053

Triad Project No. 04-20-0534 Page 11

Based on the results from the test borings, published regional geologic information and the probable maximum strength of earthquake, it is our opinion that liquefaction potential for the on-site soils during seismic activity is low to moderate. Please see Appendix E for additional seismic information.

CONSTRUCTION RECOMMENDATIONS

Site Preparation

Initial site preparation should include removing topsoil, pavement, tree stumps and other miscellaneous materials present on the site. Organic materials are not suitable for use as fill, and if encountered, should be hauled to a designated waste area. Existing utilities should be identified and protected, removed or relocated during construction of the proposed addition.

Site Excavations

As indicated in previous sections of this report, the carbonate bedrock present beneath the site generally weathers differentially to produce a very irregular top of rock profile.

Consequently, it is impossible to predict where rock will be encountered at locations between specific exploration points. In general, the residual soils and old fill can be excavated with conventional earth moving equipment. However, hard bedrock or large boulders will require hoe ramming for effective removal. Due to the proximity to the existing building; blasting should be prohibited for this project.

The means necessary to excavate rock are a function of the consistency/hardness of the material, the type/size of excavation equipment utilized and the effort the contractor is willing to apply. If the plans call for excavation of rock, for bidding purposes, potential contractors should be instructed to perform their own investigations as to measures necessary to excavate bedrock encountered.

Excavated materials should not be stockpiled and construction equipment should not be positioned beside open excavations, since the added load may cause a sudden collapse of the excavation side walls. The design and construction of all excavations should comply with applicable local, state, and federal safety regulations, including the current requirements of the Occupational Safety and Health Administration (OSHA). In no case should slope height, slope inclination, or excavation depth exceed those specified by OSHA or any other regulatory agencies or local authorities having jurisdiction at the construction site.

Structural Fill Material

Where fill is required to achieve design grades, it should be placed as controlled, compacted fill. Satisfactory fill includes approved on-site excavated materials, off-site borrow material (residual soils, soil/rock mixtures, and soft weathered rock) or well-graded commercial stone such as crusher run aggregate. The fill should be free of trash, wood, topsoil, organics, pyritic materials, coal, coal mine refuse, frozen material

Triad Project No. 04-20-0534 Page 12 and pieces of rock greater than 3 inches in any dimension for lift thicknesses of 9 inches or 1 inch in any dimension for lift thicknesses of 4 inches. Fill should be tested and approved prior to placement and compaction. It should be noted that highly plastic clay was encountered in several borings. This material is not acceptable for use as structural fill and should be wasted off site.

Fill Placement and Compaction

Before initiating fill placement, the exposed subgrade should be proof-rolled with appropriate construction equipment to locate soft spots or areas of excessive "pumping." Such areas should be excavated, scarified, aerated and re-compacted prior to placing fill, or should be removed and replaced with other suitable fill. If subgrades consisting of highly plastic clays (CH) are encountered, the soils should be moisture conditioned as necessary and compacted. These materials should meet 90% of the MDD with a moisture content wet of optimum (0 to plus 3% over optimum) based on Modified Proctor (ASTM D 1557).

During compaction, moisten or aerate each layer of fill, as necessary, to obtain the appropriate moisture content. Fill should not be placed on surfaces that are muddy or frozen, or have not been approved by prior testing and/or proof-rolling. Free water should be prevented from appearing on the surface during or subsequent to compaction operations.

Soil material which is removed because it is too wet to permit proper compaction may be spread and allowed to dry. Drying can be facilitated by discing, harrowing or by pulverizing until the moisture content is reduced to an acceptable level. When the soil is too dry, water may be uniformly applied to the subgrade surface or to the layer to be compacted.

Fill material compacted by heavy compaction equipment should be placed in loose layers having a 9-inch maximum thickness. Fill compacted with lightweight equipment, such as hand-operated tampers or walk-behind rollers, should be placed in loose layers not exceeding 4 inches in thickness. Fill placed adjacent to foundation walls should be compacted using lightweight equipment.

Fill for the project should be compacted to meet the following requirements based on the Modifed Proctor (ASTM D 1557):

Cohesionless Structural Fill: 95% of the MDD with moisture within +/- 2% of the optimum moisture

Cohesive Structural Fill: 90% of the MDD with moisture within +/- 2% of the optimum moisture

Groundwater

Groundwater levels were checked both during and after drilling operations, and no groundwater was encountered during drilling. We anticipate that sources of subsurface

Triad Project No. 04-20-0534 Page 13 water will likely be perched groundwater within granular alluvial soil layers and can probably be managed and removed by a gravity drainage system, sump pits and pumps or other minor dewatering procedures.

Quality Assurance and Control

We recommend that the licensed geotechnical engineer of record, Triad, be retained to monitor the construction activities to verify that the field conditions are consistent with the findings of our exploration. If significant variations are encountered, or if the design is altered, we should be notified.

The geotechnical engineer should provide personnel full time and/or part time, as necessary, to:

1. Observe final surface material removal and observe and verify proof-rolling of original subgrade prior to initial fill placement (if required);

2. Monitor and test material compaction during fill construction. Field density tests should be performed in accordance with ASTM D 6938 (nuclear method). At least three field density tests should be performed for each lift or a minimum of one test for every 2,500 square feet of fill placed to verify the required soil compaction;

3. Micropile foundation design drawings and calculations should be reviewed by

Triad Engineering prior to approval. Triad should be present during the foundation construction to observed drilling and construction techniques.

Verification of continuous bond zone without voids should be verified by Triad.

4. Observe and review all load tests performed on the micropiles.

5. Examine foundation bearing levels to confirm compliance with our recommendations, and verify that adequate support is available; and

6. Test concrete.

APPENDIX A

Illustrations

Site Location www.triadeng.com

INSTRUCTIONAL DESIGN CENTER (IDC)/DISTANCE LEARNING

CENTER (DLC) FACILITY

HARPERS FERRY, WEST VIRGINIA

TRIAD PROJECT NO: 04-20-0534

SOURCE: CHARLES TOWN,

WV, VA, MD QUADRANGLE

CHECKED BY:

TAG

DRAWN BY:

TNH

DATE:

06-02-2021

SCALE:

No Scale FIGURE NO: A-1

SITE VICINITY PLAN

BORING LOCATION PLAN

IDC/DLC FACILITY

HARPER’S FERRY, WEST VIRGINIA

10541 Teays Valley Road, Scott Depot, WV 25560

PH. (304) 755.0721 FAX. (304) 755.1880

Michael Baker International.

Project No.

For:

Date:

FIGURE

Charleston, WV

04-20-0534

April 22, 2021

A-250 ft

Scale

APPENDIX B

Field Exploration

Triad Engineering, Inc.

FIELD EXPLORATION

The subsurface exploration included a total of ten (10) test borings (B-1 through B-10) and two (2) auger probes (AP-1 and AP-2) extended to refusal on apparent bedrock.

Borings B-1 through B-6 as well as AP-1 and AP-2 were drilled withing the proposed building footprint. The remaining borings were drilled around the proposed building and in proposed parking areas. The boring locations are shown on the Boring Location Plan provided as Figure No. A-2 in Appendix A of this report. The locations of the test borings were determined by our discussions with the design team and established in the field by Triad personnel using existing site features and the preliminary site plan that was provided. Boring elevations were estimated based upon topographic survey data provided by you.

A representative of Triad was present to direct the drill crew, log recovered samples and observe groundwater conditions. The test borings were advanced to completion depths ranging from 2.5 to 22.5 feet below the existing ground surface using a track-mounted rotary drill rig equipped with continuous flight hollow stem augers. Standard Penetration Testing (SPT) and sampling was performed in accordance with ASTM D 1586 at 2.5-foot intervals from the ground surface to a depth of 10 feet and at 5-foot intervals thereafter to the termination depth in the test borings. Standard Penetration Numbers or N-values are commonly interpreted to provide an index to strength, consistency of cohesive soils, relative density of granular soils, and their ability to support foundations.

Groundwater levels were checked both during and after drilling operations. Each boring was dry during drilling. Water was observed immediately following drilling completion in borings B-1, B-3, B-4, and B-6 at depths ranging from 4.0 to 9.6 feet below the existing ground surface. It is noted that the introduction of water was necessary to core bedrock within these borings and the observed water is likely to be remnants of the water introduced during rock coring and is unlikely to be representative of groundwater levels.

Water was not observed in any boring that was not subject to rock coring.

It is emphasized that fluctuations in true groundwater levels can occur due to variations in seasonal, climatic, and environmental conditions which may not have been evident at the time of the field exploration. Consequently, groundwater levels can vary significantly from those recorded at the time measurements were taken.

The boreholes were backfilled with auger cuttings upon completion of drilling. Samples were transported to our office for temporary storage and additional analysis. The samples will be discarded after a period of 60 days unless other arrangements are made.

KEY TO IDENTIFICATION OF SOIL AND WEATHERED ROCK SAMPLES

The material descriptions on the logs indicate the visual identification of the soil and rock recovered from the exploration and are based on the following criteria. Major soil components are designated by capital letters and minor components are described by terms indicating the percentage by weight of each component. Standard Penetration Testing (SPT) and sampling was conducted in accordance with ASTM D1586. N-values in blows per foot are used to describe the relative density of coarse-grained soils or the consistency of fine-grained soils.

The MAJOR components constitute more than 50% of the sample and have the following size designation.

The MINOR components have the following percentage designation.

COMPONENT PARTICLE SIZE ADJECTIVE PERCENTAGE

Boulders Cobbles Gravel -coarse

-fine Sand -coarse

-medium -fine

Silt or Clay

12 inches plus 3 to 12 inches ¾ to 3 inches #4 to ¾ inches #10 to #4 #40 to #10 #200 to #40 Minus #200

(fine-grained soil) and some little trace

35 - 50

20 - 35

10 - 20

0 - 10

Relative Density – Coarse-grained Soils Consistency – Fine-grained Soils

Term N-Value Term N-Value

Very Loose "4 Very Soft "2

Loose 5 to 10 Soft 3 to 4

Medium Dense 11 to 30 Medium Stiff 5 to 8

Dense 31 to 50 Stiff 9 to 16

Very Dense >50 Very Stiff >16

Soil Plasticity Plasticity Index (PI) Rock Hardness

None Nonplastic Term N-Value

Low 1 to 5 Very Weathered "50/.5

Medium 5 to 20 Weathered 50/.4

High 20 to 40 Soft 50/.3

Very High over 40 Medium hard 50/.2 to 50/.1

Moisture Description Hard Auger Refusal

Dry - Dusty, dry to touch PLATE NO. 1 Slightly Moist - damp

Moist - no visible free water

Wet - visible free water, saturated

Figure No. B-1

KEY TO IDENTIFICATION OF HARD ROCK SAMPLES

The material descriptions on the logs indicate the visual identification of the rock recovered from the NQ/NX coring operations and are based on the following criteria. Core recovery is the ratio of the length of core recovered in each run to the total length of the core run in percent. Rock Quality Designation (RQD) is the ratio of the sum of the lengths of rock core pieces 4 inches or longer divided by the length of the core run or stratum in percent.

Relative Degree of Rock Hardness

Term Defining Characteristics

Very Soft Can be indented by thumb or crushed under pressure of finger and/or thumb

Soft Can be scratched by fingernail, peeled by pocket knife or crushed with pressed hammer

Medium Hard Cannot be scraped or peeled with knife but can be scratched, breaks easily with hammer blow

Hard Breaks under one or two strong hammer blows or scratched with knife with difficulty

Very Hard Breaks under several strong hammer blows with very resistant sharp edges

Rock Adjectives

Seam Thin layer (12 inches or less)

Interbedded Thin or very thin alternating seams of bedrock occurring in equal amounts

Some Significant amount of accessory material (15 to 40 percent)

Few Insignificant amount of accessory material (0 to 15 percent)

Rock Quality Designation (RQD) Recovery

Term Percent Term Percent

Very Poor

Poor

Fair

Good

Excellent

"25

26 to 50

51 to 75

76 to 90

>90

Poor

Low

Moderate

High

Very High

"25

26 to 50

51 to 75

76 to 90

>90

Rock Structure

Degree of Fracturing Thickness of Bedding

Term Spacing Term Spacing

Intensely fractured or very broken

Highly fractured or broken

Moderately fractured or blocky

Slightly Fractured

2 in.

2 in. to 8 in.

8 in. to 2 ft.

2 ft. to 6 ft.

Thinly bedded

Medium bedded

Thickly bedded

Massive

<4 in.

4 in. to 1 ft.

1 ft. to 3 ft.

>3 ft.

Dip of Bed or Fracturing PLATE NO. 2 Flat 0º to 20º

Dipping 20º to 45º

Steeply Dipping 45º to 90º

Figure No. B-2

Auger probe, no sampling of the soil overburden was performed.

- Auger refusal at 5.5 ft.

Boring Terminated at 5.5 feet.

5.5 398.5

5.0

10.0

15.0

20.0

25.0

Project Name:

Boring Location:

of

TRIAD

G ra ph ic

L og

Date Started:

D ep th fe et

CME-55 / Track

TAG

Ground Elev.:

Blow Counts

Shelby Tube

4/23/21 S am pl e N o.

Date Completed:

Boring No.:

Driller:

R Q

D

R U

N

Auger Probe

S am pl e

T yp e

AP-1

4/23/21

S tr at a

E le va tio n

Elevation was estimated from site survey.

Groundwater was not encountered during drilling.

Standard Split Spoon

Remarks:

W at er L ev el

Logger:

IDC DLC Facility04-20-0534

MATERIAL DESCRIPTION

Core Sample

S tr at a

D ep th ft)

Drill/Method:

R Q

D

S tr at a)

R ec ov er y

See Boring Location Plan

TEST BORING LOG Sheet 1

Project Number:

404.0

10541 Teays Valley Road Scott Depot, WV 25560

Phone: 304.755.0721 Fax: 304.755.1880

T R

IA

D

_C

4-

-0

B O

R

IN

G S

.G P

J T

R

IA

D

.G D

T

/2 /2

Auger probe, no sampling of the soil overburden was performed.

- Auger refusal at 2.5 ft.

Boring Terminated at 2.5 feet.

2.5 403.5

5.0

10.0

15.0

20.0

25.0

Project Name:

Boring Location:

of

TRIAD

G ra ph ic

L og

Date Started:

D ep th fe et

CME-55 / Track

TAG

Ground Elev.:

Blow Counts

Shelby Tube

4/23/21 S am pl e N o.

Date Completed:

Boring No.:

Driller:

R Q

D

R U

N

Auger Probe

S am pl e

T yp e

AP-2

4/23/21

S tr at a

E le va tio n

Elevation was estimated from site survey.

Groundwater was not encountered during drilling.

Standard Split Spoon

Remarks:

W at er L ev el

Logger:

IDC DLC Facility04-20-0534

MATERIAL DESCRIPTION

Core Sample

S tr at a

D ep th ft)

Drill/Method:

R Q

D

S tr at a)

R ec ov er y

See Boring Location Plan

TEST BORING LOG Sheet 1

Project Number:

406.0

10541 Teays Valley Road Scott Depot, WV 25560

Phone: 304.755.0721 Fax: 304.755.1880

T R

IA

D

_C

4-

-0

B O

R

IN

G S

.G P

J T

R

IA

D

.G D

T

/2

FILL, silty to clayey gravel, crushed stone, dense

Reddish brown to gray GRAVELLY CLAY with sand, stiff to very stiff

- (2.5 - 4.0 ft.) W=4.9%

Gray LIMESTONE, slight to moderate weathering, medium hard to hard

- (17.0 - 17.7 ft.) fractural zone

Boring Terminated at 19.7 feet.

S-1

S-2

S-3

S-4

2.0

8.5

19.7

13-20-23

9-6-7

8-6-5

4-16-50

60%

60%

0%

60%

100%

100%

100%

65%

50%

65%

401.5

395.0

383.8

13-20-23

9-6-7

8-6-5

4-16-50

5.0

10.0

15.0

20.0

25.0

Project Name:

Boring Location:

of

TRIAD

G ra ph ic

L og

Date Started:

D ep th fe et

CME-55 / Track

TAG

Ground Elev.:

Blow Counts

Shelby Tube

4/22/21 S am pl e N o.

Date Completed:

Boring No.:

Driller:

R Q

D

R U

N

Auger Probe

S am pl e

T yp e

B-1

Water Level Upon Completion

4/22/21

S tr at a

E le va tio n

Elevation was estimated from site survey.

Groundwater was not encountered during drilling.

Standard Split Spoon

Remarks:

W at er L ev el

Logger:

IDC DLC Facility04-20-0534

MATERIAL DESCRIPTION

Core Sample

S tr at a

D ep th ft)

Drill/Method:

R Q

D

S tr at a)

R ec ov er y

See Boring Location Plan

TEST BORING LOG

7.9 ft.

Sheet 1

Project Number:

403.5

10541 Teays Valley Road Scott Depot, WV 25560

Phone: 304.755.0721 Fax: 304.755.1880

T R

IA

D

_C

4-

-0

B O

R

IN

G S

.G P

J T

R

IA

D

.G D

T

/2

Reddish brown to brown FILL, sandy clay with gravel, stiff

Gray LIMESTONE, medium hard to hard

Boring Terminated at 3.0 feet.

S-1

S-2

2.0

3.0

4-4-6

50/1"

67%

100%

403.5

402.5

4-4-6

50/1"

5.0

10.0

15.0

20.0

25.0

Project Name:

Boring Location:

of

TRIAD

G ra ph ic

L og

Date Started:

D ep th fe et

CME-55 / Track

TAG

Ground Elev.:

Blow Counts

Shelby Tube

4/22/21 S am pl e N o.

Date Completed:

Boring No.:

Driller:

R Q

D

R U

N

Auger Probe

S am pl e

T yp e

B-2

4/22/21

S tr at a

E le va tio n

Elevation was estimated from site survey.

Groundwater was not encountered during drilling.

Standard Split Spoon

Remarks:

W at er L ev el

Logger:

IDC DLC Facility04-20-0534

MATERIAL DESCRIPTION

Core Sample

S tr at a

D ep th ft)

Drill/Method:

R Q

D

S tr at a)

R ec ov er y

See Boring Location Plan

TEST BORING LOG Sheet 1

Project Number:

405.5

10541 Teays Valley Road Scott Depot, WV 25560

Phone: 304.755.0721 Fax: 304.755.1880

T R

IA

D

_C

4-

-0

B O

R

IN

G S

.G P

J T

R

IA

D

.G D

T

/2

Brown to gray FILL, clayey gravel with sand, medium dense

- (2.5 - 4.0 ft.) W=8.4%, LL=30, PI=13 Gravel=69%, Sand=18%, Fines=13%

Gray LIMESTONE, slightly to moderately weathered, medium hard to hard

- (6.0 - 10.0 ft.) highly fractured

Boring Terminated at 17.5 feet.

S-1

S-2

S-3 6.0

17.5

4-5-15

14-7-5

4-5-50/2"

80%

33%

42%

77%

100%

80%

0%

22%

50%

401.5

390.0

4-5-15

14-7-5

4-5-50/2"

5.0

10.0

15.0

20.0

25.0

Project Name:

Boring Location:

of

TRIAD

G ra ph ic

L og

Date Started:

D ep th fe et

CME-55 / Track

TAG

Ground Elev.:

Blow Counts

Shelby Tube

4/22/21 S am pl e N o.

Date Completed:

Boring No.:

Driller:

R Q

D

R U

N

Auger Probe

S am pl e

T yp e

B-3

Water Level Upon Completion

4/22/21

S tr at a

E le va tio n

Elevation was estimated from site survey.

Groundwater was not encountered during drilling.

Standard…