B231 Addition_Geotechnical Report.pdf

LG2 Environmental Solutions, Inc.

A Sustainment and Restoration Services Company

10475 Fortune Parkway, Suite 201 Jacksonville, FL 32256

(904) 363-1686 www.lg2es.com

ENG INEE R ING SC I ENCE CONSTRUCT ION

May 20, 2022

Mr. Jamare Bates, PMP, P.E.

Black & Veatch 1776 Wilson Blvd., Suite 400 Arlington, VA 22209

Via Email: batesj@bv.com

RE: Geotechnical Investigation Report - Revised Robins Air Force Base, Building 231 Addition Robins Air Force Base, Georgia LG2 Project Number: 312022412

Dear Mr. Bates:

Pursuant to our contractual agreement, LG2 Environmental Solutions, Inc. (LG2) has conducted a limited geotechnical investigation at Robins Air Force Base, Building 231 located on Robins Air Force Base, Georgia. LG2 understands that plans for the existing onsite single-story structure are to renovate to include a second story. Geotechnical information collected and analyzed by our geotechnical engineering subcontractor resulted in professional opinions regarding planned constructability and would be considered by the Client as part of the renovation designs. Please find the detailed revised report of our findings attached.

If you have any questions or require additional information, please feel free to contact me.

Respectfully, LG2 Environmental Solutions, Inc.

Richard D. McCann, P.G.

Professional Geologist / Senior Project Manager

Attachment 1 – Report of Geotechnical Exploration

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Report of Geotechnical Exploration For

Robins Air Force Base – Building 231 Addition: FMS Electronic Warfare Support Facility

MAE Project No. 0313-0001 May 25, 2022

Prepared for:

Prepared by:

3728 Philips Highway, Suite 208 Jacksonville, Florida 32207

Phone (904) 519-6990 Fax (904) 519-6992

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3728 Philips Highway, Suite 208, Jacksonville, Florida 32207

p. 904.519.6990 www.MeskelEngineering.com

May 25, 2022

LG2 Environmental Solutions, Inc.

10475 Fortune Parkway, Suite 201 Jacksonville, Florida 32256

Attention: Mr. Rick McCann, P.G.

Reference: Report of Geotechnical Exploration Robins Air Force Base – Building 231 Addition: FMS Electronic Warfare Support Facility Houston County, Georgia MAE Project No. 0313-0001

Dear Mr. McCann:

Meskel & Associates Engineering, PLLC (MAE) has completed a geotechnical exploration for the subject project. Our work was performed in general accordance with our proposal dated May 14, 2021. The geotechnical exploration was performed to evaluate the general subsurface conditions along the perimeter of the existing one-story Building 231, and to evaluate the suitability of existing foundations to support the proposed second-story addition. This report has been updated to address comments provided by LG2 Environmental Solutions, Inc. and should supersede our report submitted on May 20, 2022 in its entirety.

As further discussed in this report, the borings generally encountered a surficial topsoil layer measuring approximately 2 inches thick, underlain by loose to very dense fine to coarse-grained sand with varying amounts of silt and clay content (SP, SP-SM, SM, SC). Layers of very stiff sandy clay (CH) were encountered at borings B-2 and B-3 at depths ranging from approximately 23.5 to 28.5 feet and 6 to 10 feet, respectively. The relative densities and consistencies of the encountered stratigraphy generally became denser with depth.

Based on our exploration and analyses, it is our opinion that the existing shallow foundation system for this structure is capable of supporting the proposed addition.

We appreciate this opportunity to be of service as your geotechnical consultant on this phase of the project. If you have any questions, or if we may be of any further service, please contact us.

Sincerely, MESKEL & ASSOCIATES ENGINEERING, PLLC

MAE Registry No.

W. Joshua Mele, P.E. Brett H. Harbison, P.E.

Project Engineer Director, Geotechnical Services Licensed, Florida No. 91015 Licensed, Georgia No. PE037919

Distribution: Mr. Rick McCann, P.G. – LG2 Environmental Solutions, Inc. 1 pdf

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Brett Harbison, State of Georgia Professional Engineer, License No.

PE037919. This item has been electronically signed and sealed by Brett Harbison, P.E. on 05/20/2022 using a Digital Signature. Printed copies of this document are not considered signed and sealed and the signature must be verified on any electronic copies.

Robins Air Force Base – Building 231 Addition: FMS Electronic Warfare Support Facility MAE Project No. 0313-0001

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TABLE OF CONTENTS

Subject Page No.

1.0 PROJECT INFORMATION

1.1 General

1.2 Project Description

2.0 FIELD EXPLORATION

2.1 Standard Penetration Test Borings

3.0 SOIL SAMPLE REVIEW AND CLASSIFICATION

4.0 GENERAL SUBSURFACE CONDITIONS

4.1 General Soil Profile

4.2 Groundwater Level

4.3 Review of the USDA Web Soil Survey Map

5.0 CONCLUSIONS AND RECOMMENDATIONS

5.1 General

5.2 Foundation Analyses and Recommendations

6.0 REPORT LIMITATIONS

FIGURES

Figure 1. Site Location Map Figure 2. Boring Location Plan Figure 3. Generalized Soil Profiles

APPENDICES

Appendix A. Soil Boring Logs Field Exploration Procedures Key to Boring Logs Key to Soil Classification

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1.0 PROJECT INFORMATION

1.1 General

Project information was provided to us by Mr. Rick McCann, P.G. with LG2 Environmental Solutions, Inc.

via several emails and telephone conversations. For our review and reference, we were also provided the following documents:

An annotated aerial obtained from Google Earth, titled Robins AFB Building 231_Geotech, undated, denoting the requested boring locations.

A copy of several sheets from the original plan set prepared by Warner Robins ALC Civil Engineering Group, dated April 11, 1986, including the Foundation Plan (Plate S-1), Roof Framing Plan (Plate S-2), Building Sections, Exterior Elevations, and Wall Sections (Plate A-2), Roof Plan, Sections and Details (Plate A-5).

A copy of several sheets from the original plan set prepared by Warner Robins ALC Civil Engineering Group, dated July 20, 1988, including the Foreign Military Sales (FMS) Electronic Warfare Support Facility Foundation / Slab Plan (Plate S1), and Addition to Building 241 Foreign Military Sales (FMS) Roof Framing Plan (Plate S2) and Sections and Details (Plates S3, S4, and S5).

A copy of the Roof Framing Plans for the proposed second-floor addition, prepared by the U.S.

Army Corps. of Engineers, dated April 2022, including Sheet ID S-121, S-131, S-200, S-201, and S- 202.

1.2 Project Description

The site for the subject project is located within Robins Air Force Base in Houston County, Georgia approximately 18 miles southeast of Macon, Georgia. The general site location is shown on Figure 1.

Based on the provided information and our discussions with Mr. McCann, we understand the existing Building 231, which has an area of approximately 20,532 square feet, will be renovated to include a second-story addition. Furthermore, we understand the plan dimensions of the existing interior column footings are 12 feet wide by 20 feet long by 2.5 feet thick, and the wall footings are 2 feet wide. We also understand that no new foundations will be constructed, nor are there plans to enlarge any of the existing foundations. Our understanding of our scope is to evaluate the subsurface conditions as encountered with respect to the application of additional loads to the existing structure foundations.

In an email dated May 12, 2022, we were provided the Foundation Plans, annotated with existing and expected additional loading conditions as tabulated below:

Interior Column Loading at Top of Footing (Original Design)

Dead Load 60 kips

Earth Pressure Load (vertical) 220 psf

Collateral Load 5 kips

Roof Live Load 14 kips

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Interior Column Loading at Top of Footing (Original Design with New Addition)

Dead Load 95 kips

Earth Pressure Load (vertical) 220 psf

Collateral Load 10 kips

Roof Live Load 18 kips

Live Load 61 kips

Exterior Column Loading at Top of Footing (Original Design)

Dead Load 40 kips

Earth Pressure Load (vertical) 520 psf

Collateral Load 3.5 kips

Roof Live Load 6.5 kips

Exterior Column Loading at Top of Footing (Original Design with New Addition)

Dead Load 82 kips

Earth Pressure Load (vertical) 520 psf

Collateral Load 7 kips

Roof Live Load 9 kips

Live Load 28 kips

Exterior Wall Loading at Top of Footing adjacent to Boring B-2 (Original Design)

Dead Load 3,000 plf

Earth Pressure Load (vertical) 1,000 psf

Collateral Load 30 plf

Roof Live Load 40 plf

Exterior Wall Loading at Top of Footing adjacent to Boring B-2 (Original Design with New Addition)

Dead Load 4,200 plf

Earth Pressure Load (vertical) 1,000 psf

Collateral Load 200 plf

Roof Live Load 400 plf

Live Load 200 plf

Exterior Wall Loading at Top of Footing adjacent to Boring B-3 (Original Design)

Dead Load 4,500 plf

Earth Pressure Load (vertical) 520 psf

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Collateral Load 400 plf

Roof Live Load 550 plf

Exterior Wall Loading at Top of Footing adjacent to Boring B-3 (Original Design)

Dead Load 7,500 plf

Earth Pressure Load (vertical) 520 psf

Collateral Load 800 plf

Roof Live Load 750 plf

Live Load 2,700 plf

The above loading conditions were considered during our analysis of the existing foundation and that of the planned second-story addition.

If actual project information varies from these conditions, then the recommendations in this report may need to be re-evaluated. Any changes in these conditions should be provided so the need for re-evaluation of our recommendations can be assessed prior to final design.

2.0 FIELD EXPLORATION

A field exploration was performed on April 27, 2022. A copy of the plan provided to us, which shows the approximate boring locations, is included as the Boring Location Plan, Figure 2. GPS coordinates for the boring locations were obtained using Google Earth and located at the site using a hand-held receiver. Each location was then marked for reference, and a utility locate request was filed with the Georgia 811 Call Center. Once the existing utilities were located or cleared, our field crew mobilized to the site. The final boring locations, as shown on Figure 2, should be considered approximate.

2.1 Standard Penetration Test Borings

To explore the subsurface conditions along the perimeter of the existing structure, we located and performed 3 Standard Penetration Test (SPT) borings, each drilled to a depth of approximately 40 feet below the existing ground surface, in general accordance with the methodology outlined in ASTM D 1586.

Split-spoon soil samples recovered during performance of the borings were visually described in the field and representative portions of the samples were transported to our laboratory for further testing and classification. A summary of the field procedures is included in Appendix A.

3.0 SOIL SAMPLE REVIEW AND CLASSIFICATION

Representative soil samples obtained during our field exploration were visually classified by a geotechnical engineer using the Unified Soil Classification System (USCS) in general accordance with ASTM D 2488. A Key to the Soil Classification System is included in Appendix A.

4.0 GENERAL SUBSURFACE CONDITIONS

4.1 General Soil Profile

Graphical presentation of the generalized subsurface conditions is presented on the Generalized Soil

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Profiles sheet, Figure 3. Detailed soil boring logs are included in Appendix A. When reviewing the soil profiles and boring logs, it should be understood that the soil conditions will vary between the boring locations.

The borings generally encountered a surficial topsoil layer measuring approximately 2 inches thick, underlain by loose to very dense fine to coarse-grained sand with varying amounts of silt and clay content (SP, SP-SM, SM, SC). As exceptions, borings B-2 and B-3 encountered layers of very stiff clay (CH) between depths of 23.5 to 28.5 feet and 6 to 10 feet, respectively. Finally, boring B-3 encountered a layer of very stiff silt (MH) from 38.5 to 40 feet. The relative densities of the encountered stratigraphy generally became denser with depth.

4.2 Groundwater Level

The groundwater level was only encountered at one boring locations (boring B-2) at an approximate depth of 39 feet below the existing grade. However, it should be anticipated that the groundwater levels will fluctuate seasonally and with changes in climate. As such, we recommend that the water table be remeasured prior to construction. Measured groundwater level for this boring is shown on the Generalized Soil Profiles sheet, Figure 3, and on the soil boring logs. The notation GNE (Groundwater Not Encountered) is shown for the boring locations for which groundwater was not encountered within the vertical reaches explored.

4.3 Review of the USDA Web Soil Survey Map

A review of the USDA Soil Survey Conservation Service (SSCS) Web Soil Survey of Houston and Peach Counties show that there are two predominant soil map units at the project site as tabulated below. The soil drainage class, hydrological group, and estimated seasonal high groundwater levels reported in the Soil Survey are as follows:

Map Unit

Symbol Map Unit Name Drainage Class Hydrologic

Group

Depth to the Water Table(1)

(inches)

LcB Lucy sand, 0 to 5 percent slopes Well Drained B More than 80

NgA Norfolk loamy fine sand, 0 to 2 percent slopes Well Drained B 40 to 72

(1) The “Water table” above refers to a saturated zone in the soil which occurs during specified months, typically the summer wet season. Estimates of the upper limit shown in the Web Soil Survey are based mainly on observations of the water table at selected sites and on evidence of a saturated zone, namely grayish colors (redoximorphic features) in the soil. A saturated zone that lasts for less than a month is not considered a water table.

5.0 CONCLUSIONS AND RECOMMENDATIONS

5.1 General

The following evaluation and recommendations are based on the provided project information as presented in this report, and the results of the field exploration and engineering analyses performed. If the described project conditions are incorrect or changed after this report, or if subsurface conditions encountered during construction are different from those reported, then MAE should be notified so that these recommendations can be re-evaluated and revised, if necessary.

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5.2 Foundation Analyses and Recommendations

Based on the results of our exploration, we consider the subsurface conditions at the site suitable for support of the proposed second-story structure addition on the existing shallow foundation system.

Based on our analyses, the following parameters may be used for existing foundation considerations.

5.2.1 Bearing Pressure

The maximum allowable net soil bearing pressure for use in shallow foundation design should not exceed 3,500 psf. Net bearing pressure is defined as the soil bearing pressure at the foundation bearing level in excess of the natural overburden pressure at that level.

Based on the provided loading conditions as tabulated in Section 1.2 and our calculations, the proposed second-story addition will increase the bearing pressure by approximately 450 psf on the existing column footings and 1,000 plf on the existing wall footings. Based on our calculations, this increase in pressure does not exceed the maximum allowable net soil bearing pressure beneath the existing foundation elements at this site.

5.2.2 Modulus of Subgrade Reaction

The Modulus of Subgrade Reaction (ks) is defined as the as the ratio of stress to deformation of the subgrade soils at the pressure surface. Based on the uncertainty of the soil type underlaying the existing foundation elements of this structure, we recommend a maximum value of 60 pci.

5.2.3 Friction Factor for Dissimilar Material

Based on the subsurface conditions encountered in the borings, we recommend that a coefficient of friction between the concrete and the silty sand/clayey sand interface along the existing cast-in-place concrete walls of 0.4 may be used.

5.2.4 Settlement Estimates

Post-construction settlements of the existing structure will be influenced by interrelated factors, such as

(1) subsurface stratification and strength/compressibility characteristics; and (2) footing size, bearing level, applied additional loads, and resulting bearing pressures beneath the foundations. Our settlement estimates for the structure are based on the provided plans, loading conditions, and our review of the existing soil stratigraphy encountered along the perimeter of the existing structure. Any deviation from the information as provided to us for our review and consideration may result in an increase in the estimated post-construction settlements of the structure.

Due to the predominately sandy nature of the near-surface soils, we expect the majority of settlement to occur in an elastic manner and fairly rapidly during construction. Using the applied bearing pressure, based on the supplied additional structural loads, and the field test data that we have correlated to geotechnical strength and compressibility characteristics of the subsurface soils, we estimate that the additional total settlement of the structure due to the planned additional loads could be on the order of one inch or less.

Differential settlements result from differences in applied bearing pressures and variations in the compressibility characteristics of the subsurface soils. Because of the general uniformity of the subsurface conditions, we anticipate that differential settlements of the structure could be on the order of 0.5 inches or less.

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6.0 REPORT LIMITATIONS

This report has been prepared for the exclusive use of LG2 Environmental Solutions, Inc., and their clients for specific application to the design and construction of the Robins Air Force Base – Building 231 Addition project. An electronically signed and sealed version, and a version of our report that is signed and sealed in blue ink, may be considered an original of the report. Copies of an original should not be relied on unless specifically allowed by MAE in writing. Our work for this project was performed in accordance with generally accepted geotechnical engineering practice. No warranty, express or implied, is made.

The analyses and recommendations contained in this report are based on the data obtained from this project. This testing indicates subsurface conditions only at the specific locations and times, and only to the depths explored. These results do not reflect subsurface variations that may exist away from the boring locations and/or at depths below the boring termination depths. Subsurface conditions and water levels at other locations may differ from conditions occurring at the tested locations. In addition, it should be understood that the passage of time may result in a change in the conditions at the tested locations.

If variations in subsurface conditions from those described in this report are observed during construction, the recommendations in this report must be re-evaluated.

The scope of our services did not include any environmental assessment or testing for the presence or absence of hazardous or toxic materials in the soil, groundwater, or surface water within or beyond the subject site. Any statements made in this report, and/or notations made on the generalized soil profiles or boring logs, regarding odors or other potential environmental concerns are based on observations made during execution of our scope of services and as such are strictly for the information of our client.

No opinion of any environmental concern of such observations is made or implied. Unless complete environmental information regarding the site is already available, an environmental assessment is recommended.

If changes in the design of the second-story structural addition occur, the conclusions and recommendations contained in this report may need to be modified. We recommend that these changes be provided to us for our consideration. MAE is not responsible for conclusions, interpretations, opinions or recommendations made by others based on the data contained in this report.

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Site Location Map

PREPARED BY PROJECT NAME

Robins Air Force Base-Building Addition Houston County, Georgia

REFERERENCE SCALE

Delorme XMap 7.0 NTS

PREPARED FOR MAE PROJECT NO. FIGURE NO.

LG2 Environmental Solutions, Inc. 0313-0001 1

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FIELD EXPLORATION PROCEDURES

Standard Penetration Test (SPT) Borings

The Standard Penetration Test (SPT) boring(s) were performed in general accordance with the latest revision of ASTM D 1586, “Standard Test Method for Standard Penetration Test (SPT) and Split-Barrel Sampling of Soils.” The borings were advanced by drilling techniques. A split-barrel sampler was inserted to the borehole bottom and driven 18 to 24 inches into the soil using a 140-pound hammer falling an average of 30 inches per hammer blow. The number of hammer blows for the final 12 inches of penetration (18” sample) or for the sum of the middle 12 inches of penetration (24” sample) is termed the “penetration resistance, blow count, or N-value.” This value is an index to several in-situ geotechnical properties of the material tested, such as relative density and Young’s Modulus.

After driving the sampler, it was retrieved from the borehole and representative samples of the material within the split-barrel were containerized and sealed. After completing the drilling operations, the samples for each boring were transported to the laboratory where they were examined by a geotechnical engineer to verify the field descriptions and classify the soil, and to select samples for laboratory testing.

Once the boring is complete and the groundwater level is measured, the borehole is backfilled with soil, or it is backfilled from bottom to top with a lean cementitious grout.

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K E Y T O B O R I N G L O G S – U S C S

S o i l C l a s s i f i c a t i o n

Soil classification of samples obtained at the boring locations is based on the Unified Soil Classification System (USCS). Coarse grained soils have more than 50% of their dry weight retained on a #200 sieve. Their principal descriptors are: sand, cobbles and boulders. Fine grained soils have less than 50% of their dry weight retained on a #200 sieve. They are principally described as clays if they are plastic and silts if they are slightly to non-plastic.

Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency.

BORING LOG LEGEND

Symbol Description

N Standard Penetration Resistance, the number of blows required to advance a standard spoon sampler 12" when driven by a 140-lb hammer dropping 30".

WOR Split Spoon sampler advanced under the weight of the drill rods WOH Split Spoon sampler advanced under the weight of the SPT hammer 50/2” Indicates 50 hammer blows drove the split spoon 2 inches; 50 Hammer blows for less than 6-inches of split spoon driving is considered “Refusal”.

(SP) Unified Soil Classification System -200 Fines content, % Passing No. 200 U.S. Standard Sieve w Natural Moisture Content (%) OC Organic Content (%) LL Liquid Limit PI Plasticity Index

NP

PP

Non-Plastic Pocket Penetrometer in tons per square foot (tsf)

MODIFIERS RELATIVE DENSITY (Coarse-Grained Soils) Relative Density N-Value *

SECONDARY CONSTITUENTS Very Loose Less than 3 (Sand, Silt or Clay) Loose 3 to 8

Trace Less than 5% Medium Dense 8 to 24 With 5% to 12% Dense 24 to 40

Sandy, Silty or Clayey 12% to 35% Very Dense Greater than 40 Very Sandy, Very Silty or Very Clayey 35% to 50%

CONSISTENCY (Fine-Grained Soils) ORGANIC CONTENT Consistency N-Value *

Trace Less than 5% Very Soft Less than 1 Organic Soils 5% to 20% Soft 1 to 3

Highly Organic Soils (Muck) 20% to 75% Firm 3 to 6 PEAT Greater than 75% Stiff 6 to 12

Very Stiff 12 to 24 MINOR COMPONENTS Hard Greater than 24

(Shell, Rock, Debris, Roots, etc.)

Trace Less than 5% RELATIVE HARDNESS (Limestone) Few 5% to 10% Relative Hardness N-Value * Little 15% to 25% Soft Less than 50 Some 30% to 45% Hard Greater than 50

* Using Automatic Hammer

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Prefix: G = Gravel, S = Sand, M = Silt, C = Clay, O = Organic Suffix: W = Well Graded, P = Poorly Graded, M = Silty, L = Clay, LL < 50%, H = Clay, LL > 50%

Unified Soil Classification System (USCS) (from ASTM D 2487)

Major Divisions Group Symbol Typical Names

Coarse-Grained Soils More than 50% retained on the 0.075 mm (No. 200) sieve

Gravels 50% or more of coarse fraction retained on the 4.75 mm (No. 4) sieve

Clean Gravels

GW Well-graded gravels and gravel-sand mixtures, little or no fines

GP Poorly graded gravels and gravel-sand mixtures, little or no fines

Gravels with Fines

GM Silty gravels, gravel-sand-silt mixtures

GC Clayey gravels, gravel-sand-clay mixtures

Sands 50% or more of coarse fraction passes the 4.75 (No. 4) sieve

Clean Sands

SW Well-graded sands and gravelly sands, little or no fines

SP Poorly graded sands and gravelly sands, little or no fines

Sands with Fines

SM Silty sands, sand-silt mixtures

SC Clayey sands, sand-clay mixtures

Fine-Grained Soils More than 50% passes the 0.075 mm (No. 200) sieve

Silts and Clays Liquid Limit 50% or less

ML Inorganic silts, very fine sands, rock four, silty or clayey fine sands

CL Inorganic clays of low to medium plasticity, gravelly/sandy/silty/lean clays

OL Organic silts and organic silty clays of low plasticity

Silts and Clays Liquid Limit greater than 50%

MH Inorganic silts, micaceous or diatomaceous fine sands or silts, elastic silts

CH Inorganic clays or high plasticity, fat clays

OH Organic clays of medium to high plasticity

Highly Organic Soils PT Peat, muck, and other highly organic soils

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