657-507_Marion_CorrectSeisDef - Appendix - Geotech Report 1.pdf

Report Cover Page

Seismic Correction

Marion Building 14 Revised Geotechnical Engineering Report

October 24, 2025 | Terracon Project No. 15245149

Prepared for:

Above Group Inc.

Melbourne, FL 32904

11600 Lilburn Park Road

St. Louis, Missouri 63146

P (314) 692-8811

Terracon.com

Facilities | Environmental | Geotechnical | Materials

Report Cover Letter to Sign

October 24, 2025

Above Group Inc.

305 East Dr Ste H

Melbourne, FL 32904

Attn: Mr. Stephen Kazim

Re: Revised Geotechnical Engineering Report

Seismic Correction Marion Building 14

2401 W Main Street

Marion, Illinois

Terracon Project No. 15245149

Dear Mr. Kazim:

We have completed a subsurface exploration and geotechnical engineering evaluation for the referenced project in general accordance with Terracon Proposal No. P15255149 dated June 6, 2025. This revised report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork and the design and construction of foundations, floor slabs, and pavements for the project.

We appreciate the opportunity to be of service to you on this project, and we are prepared to provide construction and materials testing (CMT) services recommended in this report (please contact Mr. Dan Hurst, Dan.Hurst@terracon.com, the CMT manager). If you have any questions concerning this report or if we may be of further service, please contact us.

Sincerely, Terracon (Illinois Firm Registration No.

184.004050.006)

Joseph J. Caciola, Jr., P.E. Jamie M. Klein, P.E. (MO)

Senior Engineer Senior Engineer

Illinois No. 062.076992

Renews 11/30/2027

02/12/2026 mailto:Dan.Hurst@terracon.com

Seismic Correction Marion Building 14 | Marion, Illinois

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 Excavation Subgrade Stabilization Fill Material Types Fill Placement and Compaction Requirements Utility Trench Backfill Grading and Drainage Earthwork Construction Considerations Construction Observation and Testing

Deep Foundations Deep Foundation Design Parameters ACIP Construction Considerations Drilled Shaft Construction Considerations

Floor Slabs Floor Slab Design Parameters Floor Slab Construction Considerations

Lateral Earth Pressures Lateral Earth Pressure Design Parameters Subsurface Drainage for Below-Grade Walls

Pavements Pavement Subgrade Preparation Pavement Section Thicknesses Pavement Drainage Pavement Maintenance

General Comments

Facilities | Environmental | Geotechnical | Materials ii

Figures GeoModel

Attachments

Exploration and Testing Procedures Site Location and Exploration Plans

Exploration and Laboratory Results

Supporting Information

Note: This report was also 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 Revised Geotechnical

Engineering services performed for the proposed boiler plant to be located at 2401 W

Main Street in Marion, Illinois. The purpose of these services was to provide information and geotechnical engineering recommendations relative to:

■ Subsurface soil and rock conditions

■ Groundwater conditions

■ IBC seismic site class

■ Site preparation and earthwork

■ Foundations

■ Floor slabs

■ Pavements

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

Location and Exploration Plan. 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 Exploration Results.

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

Our original project understanding came via a request for proposal email from Above Group on May 19, 2025. Additional documents were provided during and after the field exploration to further inform our understanding of the project. A conference call also occurred with Terracon, structural engineer, and Client on August 22, 2025 to discuss subsurface conditions, preliminary recommendations, and preferred foundation types.

Project

Description

The project consists of the construction of a new boiler plant.

The plant will be located to the north of the existing boiler plant

(Building 14) which will be decommissioned and possibly demolished after utility transfer to the new plant has occurred.

Facilities | Environmental | Geotechnical | Materials 2

Item Description

Proposed

Structure

Based on provided information, we estimate the footprint of the proposed plant will be approximately 8,600 square feet.

Finished Floor

Elevation (FFE)

The FFE of the proposed building is called out as 456 ft per the provided grading drawing (Drawing No. CS200 dated

06/24/2025).

Maximum Loads

Above Group provided the following estimated structural loads.

■ Building Columns: 125 kips

■ Building Walls: 8.7 kips per linear foot (klf)

■ Heavy Equipment: 300 psf on slab on grade

Grading

Per the provided grading plan, we have estimated that up to approximately 6 feet of fill will be required to develop final grades.

Below-Grade

Structures

We understand that the proposed building includes a 1,300 square foot basement space located in its southwest corner. The top of slab elevation in the basement is approximately 441 ft

(per Drawing No. A301 dated 06/24/2025).

Further, an underground steam tunnel running from the new plant’s basement to an existing steam tunnel is planned. The top of slab elevation within the tunnel is estimated to be approximately 444 ft per Drawing No. A301.

Free-Standing

Retaining Walls We anticipate that no free-standing retaining walls are planned.

Pavements

Anticipated traffic volumes were not provided; however, the following traffic volumes were used when preparing this report:

■ Auto/light trucks: 1,000 vehicles per day

■ Light delivery and trash collection vehicles: 10 vehicles per week

■ Tractor-trailer trucks: less than 1 vehicle per week

The pavement design period is 20 years.

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.

Facilities | Environmental | Geotechnical | Materials 3

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.

Item Description

Parcel

Information

The project is located at 2401 W Main Street in Marion, Illinois.

Latitude: 37.7244, Longitude -88.9523

See Site Location

Existing

Improvements Existing buildings, walkways, driveways, and driving lanes

Current Ground

Cover

Grass lawn with walkways to the north and east of the existing building.

Existing

Topography

The elevation in the planned new building area varies from 449 to 453 feet.

Geology

Subsurface conditions revealed by the borings generally consisted of clay soils with varying amounts of sand and gravel overlying bedrock.

Based on the Geological Map provided by the United States

Geologic Survey (USGS), the subject site is located over the

Carbondale Formation. The Carbondale Formation consists of shale bedrock with smaller amounts of sandstone, limestone, and coal.

Geotechnical Characterization

We have developed a general characterization of the subsurface conditions based on the subsurface exploration, laboratory data, geologic setting, and our understanding of the project. This characterization, termed GeoModel, forms the basis of our geotechnical evaluation. Conditions observed at each boring location are indicated on the individual logs. The individual logs are in the Exploration Results and the GeoModel is 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.

Facilities | Environmental | Geotechnical | Materials 4

Model

Layer Layer Name General Description

1 Existing Fill Lean Clay with varying amounts of sand and silt

Cohesive

Soils

Lean (CL) and fat (CH) clays with varying amounts of sand

3 Silty Sand Silty Sand (SM)

4 Bedrock Sandstone, shale, and limestone bedrock

The borings were observed during drilling and shortly after completion of drilling for the presence and level of water. Groundwater was observed at depths ranging from 30 to

32 feet in Borings B-1, B-3 and B-4. Groundwater was not encountered in the other borings at these times. A longer period of time may be required for groundwater to develop and stabilize in a borehole. Longer term observations in piezometers or observation wells, sealed from the influence of surface water, are often required to define groundwater levels.

Groundwater levels may fluctuate due to seasonal variations in the amount of rainfall, runoff, and other factors not evident at the time the borings were performed. “Perched” water could occur above lower permeability soil layers and/or near the soil/bedrock interface, and “trapped” water could be present within existing fill materials. Therefore, groundwater conditions at other times may be different than the conditions encountered in our exploratory borings. The potential for water level fluctuations and perched water should be considered when developing design and construction plans and specifications for the project.

Geologic Hazards

According to the Illinois State Geological Survey, coal mining has occurred in Macoupin

County, Illinois. The project site is near a known underground coal mine. However, the exact location of the mine and the extent of its workings is uncertain. A Coal Mine Map is provided in Attachments.

Terracon’s scope of services does not include exploration or research into prior underground mining beneath the site. Evidence of mining was not encountered in our limited subsurface exploration; however, mining operations usually occur at depths greater than those explored.

Seismic Site Class

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

Design Category. The Site Class is required to determine the Seismic Design Category

Facilities | Environmental | Geotechnical | Materials 5 for a structure. The Site Class is based on the upper 100 feet of the site profile defined by a weighted average value the shear wave velocity in accordance with Chapter 20 of

ASCE 7 and the International Building Code (IBC) 2024. Based on the soil and bedrock encountered in our subsurface exploration and the average measured shear wave velocity of about 1,300 feet per second, Seismic Site Class CD can be considered for design of the project. Note that although the subsurface exploration at this site extended to a maximum depth of 46.5 feet, shear wave velocity data was obtained to 100 foot depth from our Multichannel Analysis of Surface Waves (MASW) survey.

Sulfate Content

The table below lists the results of laboratory soluble sulfate.

Boring Sample Depth (feet) Soil Description Soluble Sulfate, ASTM

C1580 (mg/kg)

B-2 3-5 ft Lean Clay (CL) Non-detectable

B-3 3-5 ft Lean Clay (CL) Non-detectable

Results of soluble sulfate testing can be classified in accordance with ACI 318 – Building

Code Requirements for Structural Concrete. Based on the results of the laboratory testing, Class S0 can be considered for design purposes.

Geotechnical Overview

Based on the results of the subsurface exploration, laboratory tests, our analyses, and provided structural loading information, it is our opinion that the new building should be supported on deep foundations to limit total and differential settlement to within typical tolerances.

Existing fill was encountered to depths of about 1 to 3 feet in the borings. The fill could extend deeper in areas not explored. The fill was variable in composition, moisture content and consistency. No documentation or records regarding the placement of this fill were provided for our review. If records are available, Terracon should be supplied with these documents to better assess the suitability of the existing fill. Further exploration and testing (e.g., test pits, geophysical testing, etc.) of the existing fills could be performed, if requested.

Foundations will extend through the existing fill; however, support of floor slabs and pavements on or above existing fill materials is discussed in this report within the

Earthwork section. Floor slabs and pavements supported on or above undocumented

Facilities | Environmental | Geotechnical | Materials 6 existing fill may experience larger-than-normal settlement that could result in cracking and other damage.

Expansive clay soils were encountered at the site. These materials have the potential to shrink and swell with seasonal fluctuations in the soil moisture content. We recommend the floor slabs and pavements be supported on at least 24 and 12 inches of low volume change (LVC) material, respectively. In areas that are currently above or less than 2 feet below the planned bottom of floor slab level, expansive clay soils should be undercut to accommodate placement of LVC material. In areas where more than 2 feet of fill will be placed below the bottom-of-floor-slab level, at least the upper 24 inches of new engineered fill should consist of LVC material. Placement of a layer of LVC material below floor slabs, as recommended in this report, will not eliminate all future subgrade volume change and resultant floor slab movements. However, use of an LVC zone should reduce the potential for subgrade volume change. Details regarding the LVC zone are provided in

Earthwork.

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 could still occur. The severity of cracking and other cosmetic damage caused by movement of the floor slabs will likely increase if any modification of the site results in excessive wetting or drying of the expansive soils.

Eliminating the risk of movement and cosmetic distress may not be feasible, but it may be possible to further reduce the risk of movement if significantly more extensive measures are used during construction. We would be pleased to discuss other construction alternatives with you upon request.

The near surface soils consist of clays which could become unstable with typical earthwork and construction traffic, especially after precipitation events. Effective drainage should be completed early in the construction sequence and maintained after construction to avoid potential issues. If possible, the grading should be performed during the warmer and drier times of the year. If grading is performed during the wetter months, an increased risk for possible undercutting and replacement of unstable subgrade will persist. 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 7

Earthwork

Site preparation, excavation, subgrade preparation and placement of engineered fill should follow the recommendations presented in this section. The recommendations presented for design and construction of earth-supported elements, including foundations, slabs, and pavements are contingent upon the recommendations outlined in this section being followed. We recommend earthwork on this project be observed and evaluated by Terracon. The evaluation of earthwork should include observation and testing of subgrade preparation, engineered fill, foundation bearing soils, and other geotechnical conditions exposed during the construction of the project.

Site Preparation

Vegetation, topsoil, and any loose, soft or otherwise unsuitable soils present within the proposed construction areas should be stripped. Based on information obtained at the boring locations, stripping depths on the order of 6 inches should be anticipated to remove the root zone materials. However, greater stripping depths may be required in areas not explored by the borings. Organic soils removed during site preparation should not be used as fill beneath the proposed new building and pavement areas.

Demolition of the existing structures should include removal of existing foundations, walls, floor slabs, pavements, sidewalks, and any loose, soft, otherwise unsuitable materials. The demolition contractor should be aware of project requirements for complete removal of existing features, observation/testing of the base of demolition excavations prior to backfilling, use of appropriate backfill materials, and proper placement/compaction/testing of backfill materials so that removal of the demolition contractor’s backfill materials and replacement under controlled conditions is not necessary when building construction commences.

Underground utility lines are likely present within the proposed construction area. If these utilities are to remain in place, we recommend that the backfill be tested by a representative of Terracon at the time of construction. If these utilities are to be relocated, the resulting trenches should be overexcavated, backfilled, and tested in accordance with the recommendations in the Earthwork section of this report. Any abandoned underground pipes, left in place, should be fully grouted.

Expansive clay soils within the planned building area should be further undercut as necessary to accommodate placement of the recommended 24-inch thick LVC layer below floor slabs or 12-inch thick LVC layer below pavements. The undercut areas should extend a minimum of 5 feet laterally outside the building wall lines or 2 feet laterally outside the edge of pavements. Undercutting to facilitate placement of the LVC layer would not be necessary in areas where more than 24 inches of fill will be placed to

Facilities | Environmental | Geotechnical | Materials 8 develop the floor slab subgrade level or 12 inches of fill will be placed to develop the pavement subgrade level.

Where existing fill materials are present following initial site stripping and initial cuts, the existing fill should then be further evaluated by a representative of Terracon by exploring using hand equipment or test pits, field density tests and/or possibly obtaining additional samples for further laboratory testing. If unsuitable materials are encountered at this time, these materials should be removed and replaced with controlled engineered fill.

Following initial stripping and any necessary undercutting, the exposed soils should be proofrolled. A Terracon representative should observe the proofrolling. Proofrolling can be accomplished using a loaded tandem-axle dump truck with a gross weight of at least

20 tons, or similarly loaded equipment. Areas that display excessive deflection

(pumping) or rutting during proofroll operations should be improved by scarification/compaction or by removal and replacement with engineered fill.

Excavation

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

Subgrade Stabilization

Due to the presence of soils with high moisture content and relatively low strength, some means of subgrade stabilization may be required to facilitate construction, especially if wet soils are encountered during site preparation or if the subgrade becomes saturated by precipitation during site preparation/earthwork operations.

In general (weather permitting), scarifying, drying and compacting the exposed subgrades is expected to be the most economical means of improving these soils prior to placing new fill. However, this option is typically less effective where soft/wet soils are more than about one foot thick. Alternatives for subgrade stabilization could include undercutting unsuitable (wet, low strength, and/or disturbed) soils followed by the addition of crushed stone aggregate (typically on the order of 12 to 18 inches thick) to improve subgrade stability, or the incorporation of a chemical additive such as portland cement or lime kiln dust. The need for stabilization, and the most appropriate type of stabilization, will be dependent upon soil, groundwater, and weather conditions at the time of construction. The proposed grading plan, the construction schedule, and construction methods will also affect selection of the stabilization method. Terracon should be retained during construction to help provide recommendations as needed.

Facilities | Environmental | Geotechnical | Materials 9

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, or pavements.

General fill is material used to achieve grade outside of these areas.

Reuse of On-Site Soil: Excavated on-site soil may be selectively reused as fill below pavement and landscaping areas.

Material property requirements for on-site soil for use as engineered fill are noted in the table below:

Fill Type

USCS

Classification Acceptable Location for Placement

Existing Fill CL

Pavement area and at depths greater than 24 inches below finished grade unless additional testing during construction confirms the material meets LVC requirements

Existing fill should be observed, tested, and approved by Terracon.

Native Fat Clays and/or

Lean to Fat Clays

(LL≥45 and/or PI≥23)

CH, CL/CH

At depths greater than 24 inches below building finished grade and 12 inches below pavement areas

Native Lean Clays

(LL<45 and PI<23) CL All locations and elevations, except where free-draining material is required

Imported Fill Materials: Imported 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.

Fill Type

USCS

Classification Acceptable Location for Placement

Low Volume Change

(LVC) material

GM

or

CL (LL<45 and

PI<23)

All locations and elevations, except where free-draining material is required

Free Draining Granular

GW, GP,

SW, SP

Less than 5% passing No. 200 sieve

Facilities | Environmental | Geotechnical | Materials 10

Fill Type

USCS

Classification Acceptable Location for Placement

1. Engineered 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.

2. IDOT CA-6 or an approved alternate gradation of crushed limestone aggregate.

3. Granular materials with less than 5 percent fines (material passing the #200 sieve), such as ASTM C33 Size No. 57 aggregate or an approved alternate gradation.

Fill Placement and Compaction Requirements

Engineered fill and general fill should meet the following compaction requirements.

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

Same as engineered fill

Minimum

Compaction

Requirements 1,2,3

98% of max. below foundations and within

1 foot of finished pavement subgrade

95% of max. above foundations, below floor slabs, and more than 1 foot below finished pavement subgrade

92% of max.

Water Content

Range

Low plasticity cohesive: -2% to +3% of optimum

High plasticity cohesive: 0 to +4% of optimum

Granular: -3% to +3% of optimum

As required to achieve min.

compaction requirements

Facilities | Environmental | Geotechnical | Materials 11

Item Engineered Fill General Fill

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

Proctor test (ASTM D 698).

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

3. 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 their representative.

Utility Trench Backfill

Any soft or unsuitable materials encountered at the bottom of utility trench excavations should be removed and replaced with engineered fill or bedding material in accordance with public works specifications for the utility to 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.

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.

Utility trenches are a common source of water infiltration and migration. Utility trenches that penetrate beneath the building should be effectively sealed to restrict water intrusion and flow through the trenches, which could migrate below the building. Each trench should be provided with 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 clay is used to construct the trench plug, the clay should be placed and compacted in accordance with the water content and compaction recommendations for structural fill provided in this report.

Facilities | Environmental | Geotechnical | Materials 12

Grading and Drainage

The site should be graded to provide effective drainage away from the building during and after construction, and these conditions should be maintained throughout the life of the structure. Accumulation of water adjacent to the structure could contribute to significant moisture increases in the subgrade soils and subsequent softening/settlement or expansion/heave, which could 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.

After building construction and landscaping have been completed, final grades should be checked to document effective drainage has been achieved. Grades around the structure should also be periodically observed 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

The Geotechnical Engineer should be retained during the construction phase of the project to observe earthwork and perform necessary tests and observations during subgrade preparation, proofrolling, placement and compaction of engineered fill, backfilling of excavations into completed subgrades, and just prior to construction of foundations, slabs, and pavements.

Care should be taken to avoid disturbance of prepared subgrades. Unstable subgrade conditions can develop during general construction operations, particularly if the soils are wetted and/or subjected to repetitive construction traffic. If unstable subgrade conditions develop, stabilization measures will need to be employed. Construction traffic over the completed subgrade should be avoided to the extent practical. If the subgrade becomes excessively wet or dry, frozen, or disturbed, the affected materials should be removed or these materials should be scarified, moisture conditioned, and compacted prior to floor slab construction.

Based on the conditions encountered in the borings, significant seepage is generally not expected in excavations for this project (e.g., for footing construction and utility installation). If seepage is encountered in excavations during construction, the contractor is responsible for designing, implementing, and maintaining appropriate dewatering methods to control seepage and facilitate construction. In our experience, dewatering of excavations in clay soils can typically be accomplished using sump pits and pumps.

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

Facilities | Environmental | Geotechnical | Materials 13 applicable local, state, and federal safety regulations. The contractor should be aware that slope height, slope inclination, and excavation depth should in no instance exceed those specified by these safety regulations. Flatter slopes than those dictated by these regulations may be required depending upon the soil conditions encountered and other external factors. These regulations are strictly enforced and if they are not followed, the owner, contractor, and/or earthwork and utility subcontractor could be liable and subject to substantial penalties. Under no circumstances should the information provided in this report be interpreted to mean that Terracon is responsible for construction site safety or the contractor’s activities. Construction site safety is the sole responsibility of the contractor who shall also be solely responsible for the means, methods, and sequencing of the construction operations.

Construction Observation and Testing

The earthwork efforts should be observed by the Geotechnical Engineer (or their representative). 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 one test for every 2,500 square feet of compacted fill in the building areas and 5,000 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 12 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.

Deep Foundations

Due to the risks associated with supporting the building on the surficial soft to medium stiff clays, we recommend the structures be supported by deep foundations that extend and derive primary capacity from the underlying bedrock. Based on discussions with the

Facilities | Environmental | Geotechnical | Materials 14 project structural engineer, we recommend the deep foundations consist of either drilled shafts or auger cast in place (ACIP) piles. Excavations for drilled shafts could be complicated due to the presence of cohesionless soils and require casing or slurry drilling. Design parameters and construction considerations are provided in the following sections.

Deep Foundation Design Parameters

Allowable compressive capacity may be computed by multiplying the end area of the shaft/pile times the end bearing value plus the area of the shaft/pile sides times the allowable skin friction within the rock socket. Due to strain incompatibility we do not recommend skin friction within the soil layers be utilized for compression loads. Note, we would not anticipate ACIP piles would penetrate the bedrock a sufficient depth to account for skin friction; therefore, ACIP pile capacity would be solely from end-bearing.

Allowable tensile capacity may be calculated using the allowable unit skin friction in uplift for the rock socket and overlying soils, neglecting end bearing, and adding the weight of the shaft/pile; only the portion of the shaft/pile which is reinforced should be considered available to resist uplift forces.

Soil and rock parameters for design of drilled shafts and ACIP piles are provided below in the following Deep Foundation Design Summary table.

Deep Foundation Design Summary

GeoModel

Layer

Allowable

Skin

Friction

(psf) 3

Allowable

End

Bearing

Pressure

(psf) 4

Effective

Unit

Weight

(pcf)

LPILE

Soil

Type

Cohesion

(psf)

Internal

Angle of

Friction

(Degrees)

Strain

Lateral

Subgrade

Modulus, k (pci)

Frost Depth

(0 to 3)

Stiff

Clay without

Free

Water

Existing Fill 200 -- 120

Stiff

Clay without

Free

Water

750 -- 0.010 100

Cohesive Soils and Silty Sand

275 -- 125

Stiff

Clay without

Free

Water

1,000 -- 0.007 250

Facilities | Environmental | Geotechnical | Materials 15

Deep Foundation Design Summary

Layer

Allowable

Skin

Friction

(psf) 3

Allowable

End

Bearing

Pressure

(psf) 4

Effective

Unit

Weight

(pcf)

LPILE

Soil

Type

Cohesion

(psf)

Internal

Angle of

Friction

(Degrees)

Strain

Lateral

Subgrade

Modulus, k (pci)

Bedrock6 2,000 30,000 130 Weak

Rock 100 psi 7 --

0.0005

10,000 psi 9

1. Design capacities are dependent upon the method of installation and quality control parameters. The values provided are estimates and should be verified when installation protocols have been finalized.

2. See Subsurface Profile in Geotechnical Characterization for more details on stratigraphy.

3. The values shown are for compressive loading only. Reduce to 2/3 of values shown for uplift loading.

The effective weight of the shaft can be added to uplift load resistance to the extent permitted by IBC.

4. Shafts should extend at least one diameter into the bearing stratum for end bearing to be considered.

5. Because sand was encountered in only one boring, we recommend utilizing these parameters for all native soils below the existing fill and above the limestone.

6. If ACIP piles will be designed to advance into this layer, the contractor should confirm the installation equipment/methods proposed are able to reach the design pile tip elevations. Additional exploration should be performed by the contractor if needed to evaluate subsurface conditions.

7. For the Weak Rock model, the unconfined compressive strength (given in psi) is input instead of the undrained shear strength.

8. For the Weak Rock model, the km value is input instead of the strain value, ε 50.

9. For the Weak Rock model, the Young’s modulus value (given in psi) is input instead of the static soil modulus parameter, k.

The above-indicated cohesion and lateral subgrade modulus values are ultimate values without factors of safety. The end bearing is an allowable parameter with a minimum factor of safety of 3. The skin friction values are allowable parameters with factors of safety of 2. The values given in the above table are based on our borings and past experience with similar soil and rock types. Lateral resistance and friction in the upper

36 inches should be ignored due to the potential effects of frost action, desiccation, and drilling disturbance.

Long-term settlement of drilled shaft or ACIP pile foundations designed and constructed in accordance with the recommendations presented in this report is expected to be about ¾ inch or less. Differential settlement between adjacent foundation elements would be expected to be less than ½ the total settlement.

When shafts or piles are used in groups, the lateral capacities of shafts/piles in the second, third, and subsequent rows of the group should be reduced as compared to the capacity of a single, independent shaft/pile. Guidance for applying p-multiplier factors to the p values in the p-y curves for each row of pile foundations within a pile group are as follows:

Facilities | Environmental | Geotechnical | Materials 16

Center to Center

Shaft/Pile Spacing 1,2

P-Multiplier, Pm

Front Row Second Row

Third and

Subsequent

Rows

3B 0.8 0.4 0.3

4B 0.9 0.65 0.5

5B 1.0 0.85 0.7

6B 1.0 1.0 1.0

1. Spacing in the direction of loading. B = shaft/pile diameter

2. For the case of a single row of shafts/piles supporting a laterally loaded grade beam, group action for lateral resistance of piles would need be considered when spacing is less than three shaft/pile diameters (measured center-to-center).

3. See adjacent figure for definition of front, second and third rows.

The load capacities provided herein are based on the stresses induced in the supporting soil strata. The structural capacity of the shafts/piles should be checked to assure they can safely accommodate the combined stresses induced by axial and lateral forces.

Lateral deflections of piles should be evaluated using an appropriate analysis method, and will depend upon the shaft’s/pile’s diameter, length, configuration, stiffness and

“fixed head” or “free head” condition. We can provide additional analyses and estimates of lateral deflections for specific loading conditions upon request. The load-carrying capacity of shafts/piles may be improved by increasing the diameter and possibly the length.

ACIP Construction Considerations

Regarding construction of ACIP piles, we expect that it will not be difficult to penetrate the upper soils. If practical drilling refusal is experienced above the planned termination depth then a boulder or other obstruction may be present, and a replacement pile may be required. If this occurs, the situation should be evaluated by the Geotechnical

Engineer and the Structural Engineer during the foundation installation operations.

Continued “hard” drilling to attempt to extend through an obstruction or advance piles through weathered shale to reach the design bearing elevation should not be performed due to the possibility of excessive soil removal.

Proper installation of ACIPs is highly operator dependent and requires a greater than average dependence on quality workmanship and quality control monitoring. In addition, Facilities | Environmental | Geotechnical | Materials 17 the successful completion of ACIPs largely depend on the equipment and installation procedures. The auger should be withdrawn in a controlled manner and a sufficient head of grout should always be maintained in the augers, to prevent necking of fluid grout due to hydrostatic pressures.

Based on our experience, typical ACIP pile diameters range from 14 to 36 inches. Installation of adjacent piles with a clear distance spacing of less than ten pile diameters should be delayed until grout in the initial pile has set. This is required to avoid possible grout intrusion between the piles, which could jeopardize pile integrity.

The ACIP installation process should be performed under the direction of the

Geotechnical Engineer. The Geotechnical Engineer should document the pile installation process including soil/rock and groundwater conditions encountered, consistency with expected conditions, and details of the installed pile.

Drilled Shaft Construction Considerations

Groundwater was encountered in Borings B-1, B-3, and B-4, and may be present in drilled shaft excavations. To prevent collapse of the sidewalls and/or to control groundwater seepage, the use of temporary steel casing and/or slurry drilling procedures may be required for construction of drilled shaft foundations, especially given the soft and submerged cohesionless soils encountered in the borings. Significant seepage could also occur in case of excavations penetrating water-bearing sand or sandy soils. We recommend the drilled shaft contractor refer to the boring logs and evaluate proper installation methods.

Concrete should be placed soon after excavating to reduce bearing surface disturbance. We recommend the Geotechnical Engineer be retained to observe the foundation bearing materials. Any water that accumulates in the shaft excavation should be pumped from the excavation or the water level should be allowed to stabilize and then concrete should be placed using the tremie method.

If concrete will be placed as the temporary casing is being removed, we recommend the concrete mixture be designed with a slump of about 5 to 7 inches to reduce the potential for arching when removing the casing. While removing the casing from a shaft excavation during concrete placement, the concrete inside the casing should be maintained at a sufficient level to resist any earth and hydrostatic pressures outside the casing during the entire casing removal procedure.

We recommend that a representative of Terracon be present during drilling activities to evaluate the materials removed from the drilled shaft excavations to document that adequate bearing materials have been reached at the base of the excavation, to observe the base of the drilled shaft excavation to document that the cuttings have been adequately removed, and also to observe concrete placement.

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Gas could potentially be encountered in the drilled shaft excavations during construction.

Although we do not expect (or recommend) that personnel will enter the shaft excavation, the contractor should check for gases and/or oxygen deficiency in the event that any workers need to enter the excavation. Casing will be required if personnel enter the excavation.

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.

Existing fill materials were encountered at the site to a depth of 1 to 3 feet below existing grade in the building addition area. As previously described, any existing fill present beneath floor slabs should be further evaluated by Terracon during construction.

Floor Slab Design Parameters

Item Description

Floor Slab

Support1 At least 24 inches of low volume change (LVC) material

Granular Leveling

Course Layer

Thickness 2

4 inches (minimum)

Estimated Modulus of Subgrade

Reaction 3

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

1. Floor slabs should be structurally independent of building footings or walls to reduce the possibility of floor slab cracking caused by differential movements between the slab and foundation.

2. Well graded crushed stone (e.g., IDOT CA-6) or open-graded crushed stone

(e.g., ASTM C33, Size No. 57 aggregate) can be used as the leveling course.

These granular materials can be considered part of the LVC zone.

3. 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.

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

Facilities | Environmental | Geotechnical | Materials 19 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.

Joints should be placed in slabs at regular intervals as recommended by ACI to help control the locations of cracks. Joints or any cracks that develop in the floor slab should be sealed with a waterproof, non-extruding compressible compound.

If 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.

Settlement of floor slabs supported on existing fill materials cannot be accurately predicted but could be larger than normal and result in some cracking. Mitigation measures, as noted in 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

The subgrade should be maintained within the moisture content range recommended for engineered fill until the floor slab is constructed. If the subgrade becomes excessively wet or dry prior to construction of the floor slab, the affected material should be removed or the materials should be scarified, moisture conditioned, and compacted.

Upon completion of grading operations in the building area, care should be taken to maintain the subgrade within the moisture content and density ranges recommended for engineered fill prior to construction of the building floor slab.

On most project sites, the site grading is generally accomplished early in the construction phase. However, as construction proceeds, the subgrade may be disturbed due to utility excavations, construction traffic, desiccation, rainfall etc. As a result, the floor slab subgrade soils may not be suitable for placement of the granular course and/or concrete at the time of building construction, and corrective action may be required.

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.

Facilities | Environmental | Geotechnical | Materials 20

Lateral Earth Pressures

Lateral Earth Pressure Design Parameters

Structures with unbalanced backfill levels on opposite sides should be designed for earth pressures at least equal to values indicated in the following table. Earth pressures will be influenced by structural design of the walls, conditions of wall restraint, methods of construction, methods and degree of compaction, and the strength of the materials being restrained. Two wall restraint conditions are shown in the diagram below. The parameters for the “at-rest” condition presented below assumes no wall movement and would be appropriate for use in the design of the basement and below grade steam tunnel walls under static conditions. Active earth pressure is commonly used for design of free-standing cantilever retaining walls where wall movement is acceptable. The recommended design lateral earth pressures do not include a factor of safety. The drained parameters do not provide for possible hydrostatic pressure on the walls.

Lateral Earth Pressure Design Parameters

Earth

Pressure

Condition 1

Coefficient for

Backfill Type 2,3

Surcharge

Pressure 4 p1 (psf)

Equivalent Fluid Unit Weight

(pcf) 2,5

Drained 5 Undrained 5

At-Rest (Ko) Granular - 0.47 (0.47)S 60 90

Passive (Kp) Granular - 3.3 --- 420 290

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

2. Uniform, horizontal backfill, with a maximum unit weight of 130 pcf for granular soils.

3. Granular material backfill phi = 32 degrees (minimum)

Facilities | Environmental | Geotechnical | Materials 21

4. Uniform surcharge, where S is surcharge pressure.

5. Loading from heavy compaction equipment is not included.

6. To achieve “Drained” conditions, follow guidelines in Subsurface Drainage for

Below-Grade Walls below. “Undrained” conditions are recommended when drainage behind walls is not incorporated into the design.

Further, we understand this project requires below-grade walls to be designed to resist dynamic seismic lateral earth pressures. Therefore, based on the Mononobe Okabe approximation method, we recommend the following equations be utilized for dynamic analyses:

■ For yielding walls: (3/8)(kH)(backfill phi)(H2)

■ For nonyielding walls: (kH)(backfill phi)(H2)

Where: kH is equal to the peak ground acceleration (PGA) and

H is equal to the height of the backfill behind the wall.

These equations…