626A4_22_700_Murfreesboro_EHRM_Geo_Report_18235020.pdf

Report Cover Page

MCR (Main Computer Room) Addition at VAMC–Alvin C.

York Campus

Geotechnical Engineering Report

May 16, 2023 | Terracon Project No. 18225020

Prepared for:

GDM, Inc.

2600 The American Rd SE Ste 100

Rio Rancho, NM 87124

1922 Old Murfreesboro Pike, Bldg 900, Ste 905

Nashville, TN 37217

P (615) 333-6444

Terracon.com

Facilities | Environmental | Geotechnical | Materials

Report Cover Letter to Sign

May 16, 2023

GDM, Inc.

2600 The American Rd SE Ste 100

Rio Rancho, NM 87124

Attn: Mr. Eric Shreve

P: 505-429-2317

E: eshreve@GDM-AE.com

Re: Geotechnical Engineering Report

MCR (Main Computer Room) Addition at VAMC–Alvin C. York Campus

3400 Lebanon Pike (Hwy 231)

Murfreesboro, TN

Terracon Project No. 18225020

Dear Mr. Shreve:

We have completed the scope of Geotechnical Engineering services for the above referenced project in general accordance with Terracon Proposal No. P18225069 dated

March 6, 2023. This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork and the design and construction of foundations and slabs for the proposed project.

We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report or if we may be of further service, please contact us.

Sincerely, Terracon

Hossein Alimohammadi, P.E. Ashfaq A. Memon, P.E.

Senior Staff Engineer Senior Engineer

MCR (Main Computer Room) Addition at VAMC–Alvin C. York Campus | Murfreesboro, TN

Facilities | Environmental | Geotechnical | Materials i

Table of Contents Introduction

Project Description

Site Conditions

Geotechnical Characterization

Geologic Hazards

Seismic Site Class

Geotechnical Overview

Earthwork

Site Preparation

Subgrade Preparation

Excavation

Soil Stabilization

Fill Material Types

Fill Placement and Compaction Requirements

Utility Trench Backfill

Grading and Drainage

Earthwork Construction Considerations

Construction Observation and Testing

Shallow Foundations

Design Parameters – Compressive Loads

Construction Adjacent to Existing Building

Foundation Construction Considerations

Floor Slabs

Floor Slab Design Parameters

Floor Slab Construction Considerations

General Comments

Figures GeoModel

Attachments

Exploration and Testing Procedures Photography Logs

Site Location and Exploration Plans

Exploration and Laboratory Results

Supporting Information

Facilities | Environmental | Geotechnical | Materials ii

Note: This report was originally delivered in a web-based format. Blue Bold text in the report indicates a referenced section heading. The PDF version also includes hyperlinks which direct the reader to that section and clicking on the logo will bring you back to this page. For more interactive features, please view your project online at client.terracon.com.

Refer to each individual Attachment for a listing of contents.

http://client.terracon.com/

Facilities | Environmental | Geotechnical | Materials 1

Introduction

This report presents the results of our subsurface exploration and Geotechnical

Engineering services performed for the proposed MCR (Main Computer Room) Addition at Alvin C. York Campus located at 3400 Lebanon Pike (Hwy 231) in Murfreesboro, TN.

The purpose of these services was to provide information and geotechnical engineering recommendations relative to:

■ Subsurface soil conditions

■ Groundwater conditions

■ Seismic site classification per IBC

■ Site preparation and earthwork

■ Demolition considerations

■ Foundation design and construction

■ Floor slab design and construction

The geotechnical engineering Scope of Services for this project included the advancement of test borings, laboratory testing, engineering analysis, and preparation of this report.

Drawings showing the site and boring locations are shown on the Site Location and

Exploration Plan, respectively. The results of the laboratory testing performed on soil samples obtained from the site during our field exploration are included on the boring logs in the Exploration Results section.

Project Description

Our initial understanding of the project was provided in our proposal and was discussed during project planning. A period of collaboration has transpired since the project was initiated, and our final understanding of the project conditions is as follows:

Item Description

Information

Provided

Email from Mr. Eric Shreve of GDM, Inc. to Mr. Will McCloy and other team members of Terracon. The email included scope of work of the overall renovation at the campus and the existing

VA Medical Center Campus site plan dated 11/20/2014 and some general information about this project mostly regarding other trades of construction.

Facilities | Environmental | Geotechnical | Materials 2

Item Description

Project

Description

Project includes an EHRM (electronical health records modernization) upgrade which involves creating new

Telecommunications Rooms in existing buildings and construction of a ground up computer room addition adjacent to existing building on campus at one of the three different possible locations. Three possible locations are located inside the inner courtyard that has a covered gateway.

Proposed

Structure One single story, -grade 2,000+ sf, MCR building addition

Building

Construction

Load-bearing masonry walls

Possible basement or crawlspace under part of the new addition to match the tunnel or crawlspace of the existing building or corridor adjacent to new addition. Remaining portion of building addition is expected to be slab-on-grade

Finished Floor

Elevation

Unknow but anticipated to match the existing buildings finished floor elevations

Maximum Loads

■ Columns: 30 kips

■ Walls: 2 kips per linear foot (klf)

■ Slabs: 120 pounds per square foot (psf)

Grading/Slopes

A grading plan was not available. We assumed up to 2 feet of cut/fill may be required to develop final grades. Final slope angles of as steep as 3H:1V (Horizontal: Vertical) are flatter are assumed.

Below-Grade

Structures

Possible basement or crawlspace under part of the new addition to match the tunnel or crawlspace of the existing building

Free-Standing

Retaining Walls

Retaining walls are not expected to be constructed as part of site development to achieve final grades.

Building Code 2018 IBC

Terracon should be notified if any of the above information is inconsistent with the planned construction, especially the grading limits, as modifications to our recommendations may be necessary.

Site Conditions

The following description of site conditions is derived from our site visit in association with the field exploration and our review of publicly available geologic and topographic maps.

Facilities | Environmental | Geotechnical | Materials 3

Parcel

Information

The project is located at 3400 Lebanon Pike (Hwy 231) in

Murfreesboro, TN.

Less than 0.1 Acre addition area

35.9145°/ -86.3793° (approximate) (See Exhibit D)

Existing

Improvements

Existing Medical Center buildings, landscapes, sidewalks, paved parking lots and drive areas around the proposed construction area

Current Ground

Cover

Landscaping material, grass, sidewalk, asphalt pavement and a few trees

Existing

Topography

A topographic survey was not provided but existing grades are assumed to be relatively flat with less than 2 feet of relief across the proposed addition areas.

We also collected photographs at the time of our field exploration program(s) and select samples. Representative photos are provided in our Photography Log.

Geotechnical Characterization

We have developed a general characterization of the subsurface conditions based upon our review of the subsurface exploration, laboratory data, geologic setting and our understanding of the project. This characterization, termed GeoModel, forms the basis of our geotechnical calculations and evaluation of the site. Conditions observed at each exploration point are indicated on the individual logs. The individual logs can be found in the Exploration Results and the GeoModel can be found in the Figures attachment of this report.

As part of our analyses, we identified the following model layers within the subsurface profile. For a more detailed view of the model layer depths at each boring location, refer to the GeoModel.

Model

Layer Layer Name General Description

Surface cover

Approximately 3 inches of topsoil

Fill Lean clay with varying amounts of roots and limestone fragments

Lean Clay, Lean to Fat

Clay

Low plasticity clay with varying amount of chert, mineral nodules and silt, medium stiff to very stiff

Facilities | Environmental | Geotechnical | Materials 4

Model

Layer Layer Name General Description

Fat Clay High plasticity clay with trace limestone fragments, chert, mineral nodules, soft to very stiff

Borings B-1 and B-2 were drilled within the northern potential MCR addition area.

Borings B-3 and B-4 were drilled within the southern potential MCR addition area.

Borings B-5 and B-6 area were drilled within the eastern potential MCR addition area.

Underlying the topsoil cover, all borings except B-5 and B-6, encountered about 3 feet of existing fill consisting of lean clay with varying amounts of roots and limestone fragments. The fill encountered in several borings appears to be associated with historic grading associated with existing development. The fill exhibited erratic Standard

Penetration Test (SPT) N-values ranging from 7 to 11 blows per foot (bpf). The higher N-values are probably exaggerated due to the presence of limestone fragments within the existing fill and do not represent the true strength of the existing fill.

Natural clay (CL, CL/CH, CH) was encountered beneath the existing fill and beneath the surface cover at borings B-5 and B-6 where fill is absent and extended to auger refusal on apparent limestone bedrock at depths varying from about 8 to 9½ feet below existing grade. The natural clay is typically medium stiff to very stiff but occasionally soft based on SPT N-values varying from 3 to 20 bpf.

The following table summarizes approximate fill and auger refusal depths and elevations at each boring location.

Boring

No.

Approx. Existing

Ground

Elevation 1

Fill Thickness

(feet)

Depth to

Refusal (feet)

Approx. Auger

Refusal

Elevation

B-1 587 3 9 578

B-2 587 3 8 ½ 578 ½

B-3 588 3 8 ¼ 579 ¾

B-4 588 3 9 ½ 578 ½

B-5 584 0 8 ½ 575 ½

B-6 585 0 8 577

1. Existing ground elevations are approximate and were obtained from Google

Earth. Actual elevation may be different than shown on boring logs and discussed herein. Therefore, these elevations may be considered approximate for general illustration purpose. If precise elevations are desired boring locations should be surveyed.

Facilities | Environmental | Geotechnical | Materials 5

Groundwater Conditions

Groundwater was not observed in the borings while drilling, or for the short duration the borings could remain open. This does not necessarily mean the borings terminated above groundwater, or the water levels summarized above are stable groundwater levels. Due to the low permeability of the soils encountered in the borings, a relatively long period may be necessary for a groundwater level to develop and stabilize in a borehole. Long term observations in piezometers or observation wells sealed from the influence of surface water are often required to define groundwater levels in materials of this type.

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. Therefore, groundwater levels during construction or at other times in the life of the structure may be higher or lower than the levels indicated on the boring logs. Perched water can also develop on top of bedrock or within the porous fill material. The possibility of groundwater level fluctuations and perched water should be considered when developing the design and construction plans for the project.

Geologic Hazards

Formation Description

Stones River Group;

Ridley Limestone

Thick-bedded, brownish-gray limestone, fine-grained, with minor mottlings of magnesian limestone; slightly cherty. Thickness 90 to 150 feet.

1. Geologic Map of the Nashville West Quadrangle, Tennessee published by the State of Tennessee Department of Conservation, Division of Geology

(1966).

Facilities | Environmental | Geotechnical | Materials 6

In an area of limestone bedrock, auger refusal can result on slabs of unweathered limestone suspended in the residual soil matrix ("floaters"), on rock "pinnacles" rising above the surrounding bedrock surface, in widened joints that may extend well below the surrounding bedrock surface, or on the upper surface of continuous bedrock. Several of these possible auger refusal conditions are illustrated in the adjacent figure.

The Ridley Limestone bedrock formation is known for producing several obstructions that can cause the augers to refuse above sound bedrock. These obstructions can range from floaters to rock pinnacles as illustrated in examples A, B, C, and D in the above figure. Depth to competent bedrock in areas of karst geology can vary greatly over short distances. The possibility of varying depths to bedrock should be considered when developing the design and construction plans for this project.

The site is underlain by carbonate limestone that is highly susceptible to dissolution along joints and bedding planes in the rock mass. This results in voids and solution channels within the rock strata and a highly irregular bedrock surface. The weathering of the bedrock and subsequent collapse or erosion of the overburden into these openings results in what is referred to as karst topography. Any construction in karst topography is accompanied by some degree of risk for future internal soil erosion and ground subsidence that could affect the stability of the soil supported structures. Our review of the available topographic and geologic mapping shows a few sinkhole and depressions at about ½ mile radius of the site. Furthermore, the site is close to the East Fork Stones

River and some local lakes.

Seismic Site Class

The seismic design requirements for buildings and other structures are based on Seismic

Design Category. Site Classification is required to determine the Seismic Design

Category for a structure. The Site Classification is based on the upper 100 feet of the site profile defined by a weighted average value of either shear wave velocity, standard penetration resistance, or undrained shear strength in accordance with Section 20.4 of

ASCE 7 and the International Building Code (IBC). Based on the soil properties observed at the site and as described on the exploration logs and results, our professional opinion

AUGER REFUSAL ILLUSTRATION

EXISTING GROUND

A B C D E

THIS FIGURE IS FOR ILLUSTRATIVE PURPOSES ONLY AND DOES NOT

NECESSARILY DEPICT THE SPECIFIC BEDROCK CONDITIONS AT THIS SITE

LIMESTONE

BEDROCK

NATURAL

SOIL

Facilities | Environmental | Geotechnical | Materials 7 is for that a Seismic Site Classification of C be considered for the project. Subsurface explorations at this site were extended to a maximum depth of 9 ½ feet. The site properties below the boring depth and extending to 100 feet below the lowest planned building elevation were estimated based on our experience and knowledge of geologic conditions of the general area. Additional deeper borings or geophysical testing may be performed to confirm the conditions below the current boring or test depth.

Geotechnical Overview

Based on the information obtained from our subsurface explorations, the potential sites can be developed for the proposed MCR Addition, however, due to the presence of surficial fill, low strength natural clay, and high plasticity “fat” clay, subgrade remediation and further evaluation (test pits, proofrolling, DCP testing) will be required to achieve suitable bearing and to control settlements to tolerable limits. During our study, the following geotechnical considerations were identified.

We understand that new MCR building addition will be constructed at one of the three potential addition sites at the VAMC campus. The northern and southern building addition sites where borings B-1 through B-4 were drilled appeared to be covered with existing fill which extends to a depth of about 3 feet below existing grade.

Documentation regarding fill placement and compaction was not available. Considering the presence of some organics and uncertainties associated with undocumented fill, in our opinion existing fill is suspect and is not recommended for building support.

Considering relatively small size of proposed building addition with expected closely spaced footings, , we recommend undercutting the existing fill within the entire building addition footprint to suitable natural soils. The undercut areas should be backfilled with approved engineered fill. Based on our borings, the undercut depth to remove existing fill is expected to extend to depth of about 3 feet below existing grade. The undercut soils can be reused as engineered fill after moisture conditioning provided the material meets our fill material and placement criteria as outlined herein. The new engineered fill should be compacted to at least 98 percent of material’s standard Proctor maximum dry density prior to any building construction. Any low strength soils exposed after fill removal should be further undercut/replaced or scarified and recompacted per our recommendations outlined herein.

If the new building addition is proposed in the eastern potential site where borings B-5 and B-6 were drilled, we expect suitable natural clayey soils will be encountered below building foundation and slab bearing levels. The onsite natural soils generally appear suitable for foundation and floor slab support. However, we recommend exposed subgrade at finished grade and bearing level should be thoroughly evaluated via DCP testing and proofrolling to confirm the stability of the onsite natural soils for building

Facilities | Environmental | Geotechnical | Materials 8 support. Any yielding soils discovered during proofolling and foundation observation should be undercut/replaced or recompacted.

Assuming the conditions at the boring locations are representative and the Geotechnical

Engineer is allowed to review the exposed subgrade and foundation excavations, existing fill will be undercut and replaced; the proposed building addition may be founded upon shallow spread footings bearing on stiff natural soil, and/or approved new engineered fill. An allowable design bearing pressure of 2,000 psf may be used for foundation design when subgrade is prepared as discussed herein.

High plasticity “fat” clay (CH) was encountered in a few borings below 3 feet within the proposed additionareas. Fat clay has some potential to shrink and swell with changes in moisture content. This volume change potential presents a risk of some objectionable slab movement and/or cracking in response to changes in the soil’s moisture content.

Where these soils are exposed at/near finished floor slab subgrade, the upper 1 foot of subgrade should be undercut and replaced with low volume change engineered fill

(LL<45). Delineation of fat clay should be performed in the field by a qualified geotechnical engineer.

Expansive soils are present on this site. This report provides recommendations to help mitigate the effects of soil shrinkage and expansion. However, even if these procedures are followed, some movement and (at least minor) cracking in the structure should be anticipated. The severity of cracking and other damage such as uneven floor slabs will probably increase if modification of the site results in excessive wetting or drying of the expansive soils. Eliminating the risk of movement and distress may not be feasible, but it may be possible to further reduce the risk of movement if significantly more expensive measures are used during construction. If desired Terracon will be pleased to discuss additional measures to further reduce the risk of movements.

The near surface cohesive soils are moisture sensitive and could become unstable during wet weather and under repetitive construction traffic. Therefore, effective drainage should be implemented early in the construction sequence and maintained after construction to avoid potential subgrade instability issues. We recommend the grading be performed during the warmer and drier times of the year. If grading is performed during the wet season, widespread subgrade instability issues may arise that may require undercutting and replacement of unstable subgrade. Additional recommendations

Additional site preparation recommendations, including subgrade improvement and fill placement, are provided in the Earthwork section.

The recommendations contained in this report are based upon the results of field and laboratory testing (presented in the Exploration Results), engineering analyses, and our current understanding of the proposed project. The General Comments section provides an understanding of the report limitations.

Facilities | Environmental | Geotechnical | Materials 9

Earthwork

Earthwork is anticipated to include demolition, clearing and grubbing, excavations, and engineered fill placement. The following sections provide recommendations for use in the preparation of specifications for the work. Recommendations include critical quality criteria, as necessary, to render the site in the state considered in our geotechnical engineering evaluation for foundations and floor slabs.

Site Preparation

Prior to placing new fill, existing vegetation, topsoil, trees including stumps and root mats should be removed. Complete stripping of the topsoil should be performed in the proposed building and pavement areas.

Although no evidence of underground structures (such as septic tanks, cesspools, basements, and utilities) was observed during the exploration and site reconnaissance, such features could be encountered during construction. If unexpected fills or underground facilities are encountered, such features should be removed, and the excavation thoroughly cleaned prior to backfill placement and/or construction.

Subgrade Preparation

After site clearing, stripping and completing required cut within the building addition pad, but before placing new fill, the exposed subgrade should be proofrolled to detect any near surface weak soils. Proofrolling is a very useful tool in identifying shallow areas of subgrade instability but should be performed only after a suitable period of dry weather to avoid degrading an otherwise acceptable subgrade. The subgrade should be proofrolled with an adequately loaded vehicle such as a fully-loaded tandem-axle dump truck. The proofrolling should be performed under the observation of the Geotechnical

Engineer or representative. Areas excessively deflecting under the proofroll should be delineated and subsequently addressed by the Geotechnical Engineer. Such areas should either be removed or modified by treating/applying/mixing with lime or cement.

Excessively wet or dry material should either be removed or moisture conditioned and recompacted.

Based upon the subsurface conditions determined from the geotechnical exploration, subgrade soils exposed during construction are anticipated to be relatively workable;

however, the workability of the subgrade may be affected by precipitation, repetitive construction traffic or other factors. If unworkable conditions develop, workability may be improved by scarifying and drying.

The on-site clayey soils are susceptible to disturbance and loss of strength from construction activity, particularly if the soil has a high natural moisture content and is

Facilities | Environmental | Geotechnical | Materials 10 wetted by surface water or seepage. Therefore, care should be taken during the site grading operation to provide adequate site drainage and minimize disturbance of the bearing soils. Heavy equipment traffic directly on bearing surfaces should be avoided in wet clay soils.

Excavation

We anticipate that excavations for the proposed construction can be accomplished with conventional earth moving equipment. The bottom of excavations should be thoroughly cleaned of loose soils and disturbed materials prior to backfill placement and/or construction.

Soil Stabilization

The on-site clayey soils are susceptible to disturbance and loss of strength from construction activity, particularly if the soil has a high natural moisture content and is wetted by surface water or seepage. Subgrade instability should be expected during periods of wet weather.

Where unstable soils are identified by proofrolling, methods of subgrade improvement, as described below, could include scarification, moisture conditioning and recompaction, removal of unstable materials and replacement with granular fill (with or without geosynthetics), and chemical stabilization. The appropriate method of improvement, if required, would be dependent on factors such as schedule, weather, the size of area to be stabilized, and the nature of the instability. More detailed recommendations can be provided during construction as the need for subgrade stabilization occurs. Performing site grading operations during warm seasons and dry periods would help reduce the amount of subgrade stabilization required.

If the exposed subgrade is unstable during proofrolling operations, it could be stabilized using one of the methods outlined below.

◼ Scarification and Recompaction - It may be feasible to scarify, dry, and recompact the exposed soils. The success of this procedure would depend primarily upon favorable weather and sufficient time to dry the soils. Stable subgrades likely would not be achievable if the thickness of the unstable soil is greater than about 1 foot, if the unstable soil is at or near groundwater levels, or if construction is performed during a period of wet or cool weather when drying is difficult.

◼ Crushed Stone - The use of crushed stone or crushed gravel is a common procedure to improve subgrade stability. Typical undercut depths would be expected to range from about 2 to 4 ft below finished subgrade elevation. The use of high modulus geotextiles (i.e., engineering fabric or geogrid) could also be

Facilities | Environmental | Geotechnical | Materials 11 considered after underground work such as utility construction is completed. Prior to placing the fabric or geogrid, we recommend that all below grade construction, such as utility line installation, be completed to avoid damaging the fabric or geogrid. Equipment should not be operated above the fabric or geogrid until one full lift of crushed stone fill is placed above it. The maximum particle size of granular material placed over geotextile fabric or geogrid should not exceed 1-1/2 inches.

◼ Chemical Modification - Improvement of subgrades with portland cement or class C fly ash could be considered for improving unstable soils. Chemical modification should be performed by a pre-qualified contractor having experience with successfully stabilizing subgrades in the project area on similar sized projects with similar soil conditions. Results of chemical analysis of the additive materials should be provided to the geotechnical engineer prior to use. The hazards of chemicals blowing across the site or onto adjacent property should also be considered. Additional testing would be needed to develop specific recommendations to improve subgrade stability by blending chemicals with the site soils. Additional testing could include, but not be limited to, determining the most suitable stabilizing agent, the optimum amounts required, the presence of sulfates in the soil, and freeze-thaw durability of the subgrade.

◼ Shot Rock – Clean well graded shot rock can also be used to stabilize unstable subgrade. The thickness of shot rock required to achieve bridging of the unstable subgrade will depend upon the extent of subgrade stability. A test strip should be initially prepared at the site to determine the minimum required shot rock fill thickness to achieve subgrade stability. Shot rock particle size should not exceed

12 inches and should be compacted using a heavy-duty vibratory roller or D-6 size bulldozer.

Further evaluation of the need and recommendations for subgrade stabilization can be provided during construction as the geotechnical conditions are exposed.

Fill Material Types

Fill required to achieve design grade should be classified as engineered fill and general fill. Engineered fill is material used below, or within 10 feet of structures, and pavements, concrete slabs or constructed slopes. General fill is material used to achieve grade outside of these areas.

Fill materials should meet the following material property requirements. Regardless of its source, compacted fill should consist of approved materials that are free of organic matter and debris. Frozen material should not be used, and fill should not be placed on a frozen subgrade.

Facilities | Environmental | Geotechnical | Materials 12

Soil Type

USCS

Classification

Acceptable Parameters

(for Engineered Fill)

Low Plasticity Cohesive CL

Liquid Limit < 50, Plasticity index <30

Can be used in all areas except in foundation undercut and utility trenches

High Plasticity

“Fat” Cohesive

CH

Liquid Limit > 50, or Plasticity index > 30

(should only be placed 2’ or more below pavement finished subgrade), not recommended in building pad

Granular GW

Can be used at all locations and elevations

Existing Fill CL, CH

A large portion of the existing fill can possibly be reused provided the material is free of debris and unsuitable material and meets the above fill criteria and is approved by the Geotechnical Engineer

Clean well graded processed rock, shotrock

(max. rock size

12 inches, with <5% soil) or surge stone

(max. rock size 8 inches)

Can be used at all locations and elevations. Should not be used in footing and utility trench areas where smaller excavation equipment will be used.

1. Structural and general fill should consist of approved materials free of organic matter and debris. 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 prior to use on this site.

2. CH soils should not be used in building pad.

3. Similar to TDOT Section 903.05 Type A, Grading D crushed limestone aggregate, limestone screenings, or granular material such as well graded gravel or crushed stone.

4. Approval of shot rock and surge stone should be made prior to placement. Any rock fill containing more than 5% clay fines should not be used as engineered fill.

Fill Placement and Compaction Requirements

Engineered and general fill should meet the following compaction requirements.

Facilities | Environmental | Geotechnical | Materials 13

Item Engineered Fill General Fill

Maximum Lift

Thickness

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

4 to 6 inches in loose thickness when hand-guided equipment (i.e. jumping jack or plate compactor) is used

12 to 18 inches for surge and shot rock

Same as engineered fill

Minimum

Compaction

Requirements 1,2,3

98% of max. below foundations, floor slabs, and pavements

Surge and shot rock to be compacted with heavy-duty vibratory smooth drum roller or

D-6 class dozer making ten passes (five in one direction and 5 at right angle to initial passes)

92% of max.

Water Content

Range

Low plasticity cohesive: -1% to +3% of optimum

High plasticity cohesive: 0 to +3% of optimum

Granular: -2% to +2% of optimum

As required to achieve min.

compaction requirements

5. Maximum density and optimum water content as determined by the standard

Proctor test (ASTM D 698).

6. High plasticity cohesive fill should not be compacted to more than 100% of standard Proctor maximum dry density.

7. If the granular material is a coarse sand or gravel, or of a uniform size, or has a low fines content, compaction comparison to relative density may be more appropriate. In this case, granular materials should be compacted to at least

70% relative density (ASTM D 4253 and D 4254). Materials not amenable to density testing should be placed and compacted to a stable condition observed by the Geotechnical Engineer or representative.

8. Approval of surge and shot rock should be made prior to placement. Any rock fill containing more than 5% clay fines should not be used as engineered fill.

Utility Trench Backfill

Any soft or unsuitable materials encountered at the bottom of utility trench excavations should be removed and replaced with structural fill or bedding material in accordance with project specifications for the utility be supported. This recommendation is particularly applicable to utility work requiring grade control and/or in areas where subsequent grade raising could cause settlement in the subgrade supporting the utility.

Facilities | Environmental | Geotechnical | Materials 14

Trench excavation should not be conducted below a downward 1:1 projection from existing foundations without engineering review of shoring requirements and geotechnical observation during construction.

Trench backfill should be mechanically placed and compacted as discussed earlier in this report. Compaction of initial lifts should be accomplished with hand-operated tampers or other lightweight compactors. Where trenches are placed beneath slabs or footings, the backfill should satisfy the gradation and expansion index requirements of engineered fill discussed in this report. Flooding or jetting for placement and compaction of backfill is not recommended.

For low permeability subgrades, utility trenches are a common source of water infiltration and migration. Utility trenches penetrating beneath the building should be effectively sealed to restrict water intrusion and flow through the trenches, which could migrate below the building. The trench should provide an effective trench plug that extends at least 5 feet from the face of the building exterior. The plug material should consist of cementitious flowable fill or low permeability clay. The trench plug material should be placed to surround the utility line. If used, the clay trench plug material should be placed and compacted to comply with the water content and compaction recommendations for structural fill stated previously in this report.

Grading and Drainage

All grades must provide effective drainage away from the building during and after construction and should be maintained throughout the life of the structure. Water retained next to the building can result in soil movements greater than those discussed in this report. Greater movements can result in unacceptable differential floor slab and/or foundation movements, cracked slabs and walls, and roof leaks. The roof should have gutters/drains with downspouts that discharge onto splash blocks at a distance of at least 10 feet from the building.

After building construction and landscaping have been completed, final grades should be verified to document effective drainage has been achieved. Grades around the structure should also be periodically inspected and adjusted, as necessary, as part of the structure’s maintenance program. Where paving or flatwork abuts the structure, a maintenance program should be established to effectively seal and maintain joints and prevent surface water infiltration.

Earthwork Construction Considerations

Shallow excavations for the proposed building addition are anticipated to be accomplished with conventional construction equipment. Upon completion of filling and grading, care should be taken to maintain the subgrade water content prior to

Facilities | Environmental | Geotechnical | Materials 15 construction of soil-supported improvements such as floor slabs and pavements.

Construction traffic over the completed subgrades should be avoided. The site should also be graded to prevent ponding of surface water on the prepared subgrades or in excavations. Water collecting over or adjacent to construction areas should be removed.

If the subgrade freezes, desiccates, saturates, or is disturbed, the affected material should be removed, or the materials should be scarified, moisture conditioned, and recompacted prior to floor slab construction.

As a minimum, excavations should be performed in accordance with OSHA 29 CFR, Part

1926, Subpart P, “Excavations” and its appendices, and in accordance with any applicable local and/or state regulations.

Construction site safety is the sole responsibility of the contractor who controls the means, methods, and sequencing of construction operations. Under no circumstances shall the information provided herein be interpreted to mean Terracon is assuming responsibility for construction site safety or the contractor's activities; such responsibility shall neither be implied nor inferred.

Construction Observation and Testing

The earthwork efforts should be observed by the Geotechnical Engineer (or others under their direction). Observation should include documentation of adequate removal of surficial materials (vegetation, topsoil, and pavements), evaluation and remediation of existing fill materials, as well as proofrolling and mitigation of unsuitable areas delineated by the proofroll.

Each lift of compacted fill should be tested, evaluated, and reworked, as necessary, as recommended by the Geotechnical Engineer prior to placement of additional lifts. Each lift of fill should be tested for density and water content at a frequency of at least two tests for every 2,500 square feet of compacted fill in the building areas and 300 square feet in pavement areas. Where not specified by local ordinance, one density and water content test should be performed for every 100 linear feet of compacted utility trench backfill and a minimum of one test performed for every 10 vertical inches of compacted backfill.

In areas of foundation excavations, the bearing subgrade should be evaluated by the

Geotechnical Engineer. If unanticipated conditions are observed, the Geotechnical

Engineer should prescribe mitigation options.

In addition to the documentation of the essential parameters necessary for construction, the continuation of the Geotechnical Engineer into the construction phase of the project provides the continuity to maintain the Geotechnical Engineer’s evaluation of subsurface conditions, including assessing variations and associated design changes.

Facilities | Environmental | Geotechnical | Materials 16

Shallow Foundations

If the site has been prepared in accordance with the requirements noted in Earthwork, the following design parameters are applicable for shallow foundations.

Assuming the site is repaired i.e; existing fill and any soft soils are undercut/replaced or recompacted) as directed herein, the proposed building can be supported on shallow spread footings bearing on stiff natural clay and/or approved compacted engineered fill.

Design recommendations for shallow foundations are presented below.

Design Parameters – Compressive Loads

Description Column Wall

Max. net allowable bearing pressure 2,000 psf 2,000 psf

Minimum dimensions 30 inches 18 inches

Minimum embedment below finished grade for frost protection 2 18 inches 18 inches

Approximate total settlement <1 inch <1 inch

Estimated differential settlement <¾ inch between columns

<¾ inch over 40 feet

Ultimate Passive Resistance

(equivalent fluid pressures)

295 pcf (cohesive backfill)

390 pcf (granular backfill)

Ultimate coefficient of sliding friction

0.35

Facilities | Environmental | Geotechnical | Materials 17

Description Column Wall

1. The recommended net allowable bearing pressure is the pressure in excess of the minimum surrounding overburden pressure at the footing base elevation.

This bearing pressure assumes that existing fill and any low strength natural soils where present beneath foundation bearing level will be undercut and replaced as outlined herein.

2. This is recommended for perimeter footings and footings beneath unheated areas to reduce the effects of seasonal moisture variations in the subgrade soils.

3. The foundation settlement will depend upon the variations within the subsurface soil profile, the structural loading conditions, the embedment depth of the footings, the thickness of the compacted fill, and the quality of the earthwork operations. This assumes that soil bearing subgrade will be addressed as outlined herein. These values do not take into account any foundation movement instigated by karst related ground subsidence.

4. The sides of the excavation for spread footings must be nearly vertical and the concrete should be placed neat against these vertical faces for the passive earth pressure value to be valid. If the loaded side is sloped or benched, and then backfilled, the allowable passive pressure will be significantly reduced.

Passive resistance in the upper 2 feet of the soil profile should be neglected. Lateral resistance due to friction at the base of the footing should be ignored where uplift also occurs. The above ultimate equivalent fluid pressure values are based on soil unit weight of 120 pcf.

Construction Adjacent to Existing Building

Differential settlement between the additions and the existing building is expected to approach the magnitude of the total settlement of the addition. Expansion joints should be provided between the existing building and the proposed addition to accommodate differential movements between the two structures. Underground piping between the two structures should be designed with flexible couplings and utility knockouts in foundation walls should be oversized so minor deflections in alignment do not result in breakage or distress. Care should be taken during excavation adjacent to existing foundations to avoid disturbing existing foundation bearing soils.

New footings should bear at or near the bearing elevation of immediately adjacent existing foundations. Depending upon their locations and current loads on the existing footings, footings for the new addition could cause settlement of adjacent walls. To reduce this concern and risk, clear distances at least equal to the new footing widths should be maintained between the addition’s footings and footings supporting the existing building.

We understand existing foundations may support additional load from the walls of the new additions. Additional loads on the existing foundations could cause other building

Facilities | Environmental | Geotechnical | Materials 18 settlements to occur. The structural capacity of existing foundations should be evaluated by a licensed structural engineer, where increases in loading are planned.

Foundation Construction Considerations

As noted in Earthwork, the footing excavations should be evaluated under the observation of the Geotechnical Engineer. The base of all foundation excavations should be free of water and loose soil/rock, prior to placing concrete. Concrete should be placed soon after excavating to reduce bearing soil disturbance. Care should be taken to prevent wetting or drying of the bearing materials during construction. Excessively wet or dry material or any loose/disturbed material in the bottom of the footing excavations should be removed/reconditioned before foundation concrete is placed.

Sensitive soils exposed at the surface of footing excavations may require surficial compaction with hand-held dynamic compaction equipment prior to placing structural fill, steel, and/or concrete. Should surficial compaction not be adequate, construction of a working surface consisting of either crushed stone or a lean concrete mud mat may be required prior to the placement of reinforcing steel and construction of foundations.

If unsuitable bearing soils are observed at the base of the planned footing excavation, the excavation should be extended deeper to suitable soils, and the footings could bear directly on these soils at the lower level or on lean concrete backfill placed in the excavations. The lean concrete replacement zone is illustrated on the sketch below.

Overexcavation for structural fill placement below footings should be conducted as shown below. The overexcavation should be backfilled up to the footing base elevation, with well graded granular placed, as recommended in the Earthwork section.

Facilities | Environmental | Geotechnical | Materials 19

Floor Slabs

Design parameters for floor slabs assume the requirements for Earthwork have been followed. Specific attention should be given to positive drainage away from the structure and positive drainage of the aggregate base beneath the floor slab.

As discussed earlier, the subgrade should be undercut to suitable natural soils to address existing fill, any low strength and high plasticity natural clays. The undercut area should be backfilled with approved engineered fill per our recommendations outlined herein.

Floor Slab Design Parameters

Item Description

Floor Slab

Support1

Minimum 4 inches of free draining (less than 5% passing the U.S.

No. 200 sieve) crushed aggregate compacted to at least 95% of

ASTM D 698 or #57 stone 2,3

Subgrade compacted to recommendations in Earthwork

Estimated Modulus of Subgrade

Reaction 2,3

100 pounds per square inch per inch (psi/in) for point loads

Ultimate coefficient of sliding friction

0.35

1. Modulus of subgrade reaction is an estimated value based upon our experience with the subgrade condition, the requirements noted in Earthwork, and the floor slab support as noted in this table. It is provided for point loads. For large area loads the modulus of subgrade reaction would be lower.

Facilities | Environmental | Geotechnical | Materials 20

2. Free-draining granular material should have less than 5% fines (material passing the No. 200 sieve). Other design considerations such as cold temperatures and condensation development could warrant more extensive design provisions.

3. Assumes existing fill and any unsuitable and/or soft soils encountered at bearing elevation will be remediated as discussed in Earthwork.

1. Sliding friction along the base of the foundation will not develop where net uplift conditions exist

The use of a vapor retarder should be considered beneath concrete slabs on grade covered with wood, tile, carpet, or other moisture sensitive or impervious coverings, when the project includes humidity-controlled areas, or when the slab will support equipment sensitive to moisture. When conditions warrant the use of a vapor retarder, the slab designer should refer to ACI 302 and/or ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder.

Saw-cut contraction joints should be placed in the slab to help control the location and extent of cracking. For additional recommendations, refer to the ACI Design Manual.

Joints or cracks should be sealed with a waterproof, non-extruding compressible compound specifically recommended for heavy duty concrete pavement and wet environments.

Where floor slabs are tied to perimeter walls or turn-down slabs to meet structural or other construction objectives, our experience indicates differential movement between the walls and slabs will likely be observed in adjacent slab expansion joints or floor slab cracks beyond the length of the structural dowels. The Structural Engineer should account for potential differential settlement through use of sufficient control joints, appropriate reinforcing or other means.

Mitigation measures, as noted in Existing Fill within Earthwork, are critical to the performance of floor slabs. In addition to the mitigation measures, the floor slab can be stiffened by adding steel reinforcement, grade beams, and/or post-tensioned elements.

Floor Slab Construction Considerations

Finished subgrade, within and for at least 10 feet beyond the floor slab, should be protected from traffic, rutting, or other disturbance and maintained in a relatively moist condition until floor slabs are constructed. If the subgrade should become damaged or desiccated prior to construction of floor slabs, the affected material should be removed, and structural fill should be added to replace the resulting excavation. Final conditioning of the finished subgrade should be performed immediately prior to placement of the floor slab support course.

Facilities | Environmental | Geotechnical | Materials 21

Prior to construction of grade supported slabs, varying levels of remediation may be required to reestablish stable subgrades within slab areas due to construction traffic, rainfall, disturbance, desiccation, etc. As a minimum, the following measures are recommended.

◼ Confirm that interior trench backfill placed beneath slabs is compacted in accordance with recommendations outlined in this report.

◼ All floor slab subgrade areas should be moisture-conditioned and properly compacted to the recommendations in this report immediately prior to placement of the stone base and concrete.

The Geotechnical Engineer should observe the condition of the floor slab subgrades immediately prior to placement of the floor slab support course, reinforcing steel, and concrete. Attention should be paid to high traffic areas that were rutted and disturbed earlier, and to areas where backfilled trenches are located.

General Comments

Our analysis and opinions are based upon our understanding of the project, the geotechnical conditions in the area, and the data obtained from our site exploration.

Variations will occur between exploration point locations 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. Terracon should be retained as the

Geotechnical Engineer, where noted in this report, to provide observation and testing services during pertinent construction phases. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on-site, we should be immediately notified so that we can provide evaluation and supplemental recommendations.

Our Scope of Services 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.