Hartford Federal Courthouse Prelim Geo Rpt (GEI 09 15 25).pdf

Preliminary Geotechnical Report

New Federal Courthouse Allyn Street Hartford, Connecticut

Submitted to:

Michael Maltzan Architecture, Inc.

2801 Hyperion Avenue, Studio 107

Los Angeles, CA 90027

Submitted by:

GEI Consultants, Inc.

455 Winding Brook Drive, Suite 201

Glastonbury, CT 06033

860-368-5300

September 15, 2025

Project No. 2503909

Majid Mahmoodabadi, P.E. (MI)

Geotechnical Professional

Matthew Glunt, P.E.

Senior Geotechnical Engineer

Consulting

Engineers and

Scientists

P R E L I M I N A R Y G E O T E C H N I C A L R E P O R T N E W F E D E R A L C O U R T H O U S E H A R T F O R D , C O N N E C T I C U T S E P T E M B E R 1 5 , 2 0 2 5

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Table of Contents

1. Introduction 1

1.1 Project Summary 1

1.2 Purpose and Scope 1

1.3 Authorization 2

1.4 Vertical and Horizontal Reference 2

2. Site and Project Description 3

2.1 Site Description and History 3

2.2 Proposed Construction 3

3. Exploration Procedures 4

3.1 Test Borings 4

3.2 Monitoring Wells 4

3.3 Shear Wave Velocity Measurements 4

3.4 Geotechnical Laboratory Testing 5

3.5 Soil Corrosivity Testing 5

3.6 Previous Investigations 5

4. Subsurface Conditions 6

4.1 Geologic Setting 6

4.2 Subsurface Conditions 6

4.3 Groundwater 8

5. Design Considerations 11

5.1 General Suitability 11

5.2 Foundation Support Options 11

5.2.1 Ground Improvements 12

5.2.2 Drilled Foundations 13

5.2.3 Driven Foundations 13

5.3 Lower-level Floor Slab 13

5.4 Seismic Design 13

5.5 Lateral Support 14

5.6 Foundation Drainage 15

6. Construction Considerations 16

6.1 Subgrade Preparation 16

6.2 Excavation and Shoring 16

6.3 Dewatering 17

6.4 Protection of Existing Structures 17

6.5 Soil Re-use 17

7. Closure 18

7.1 Limitations 18

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Figures

1 Test Location Plan

Appendices

A Boring and Monitoring Well Logs

B Laboratory Test Results

C Shear Wave Velocity Testing Report

D Previous Investigation Data

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1. Introduction

1.1 Project Summary

The approximately 2.19-acre assemblage site slated for development is bounded by Allyn

Street to the south, High Street to the west, and Church Street to the north in downtown

Hartford, Connecticut.

Project design plans are in the conceptual stages, though we understand at this time that new construction is to consist of a 9-story federal courthouse facility with one (1) underground parking level.

1.2 Purpose and Scope

We understand this project will be delivered using a Design-Build process. These services were provided under the Pre-Award Concept phase, with this report to be incorporated into the Design-Build bid documents. As such, the goals of this initial phase of investigation were to:

• Evaluate subsurface conditions below the site with particular focus on high-risk items for cost planning.

• Develop preliminary considerations for site development and building construction, including identifying any primary cost drivers and non-standard construction that may be required to suit conditions.

To that end, GEI’s scope of services during this phase of the project included the following:

• Reviewed provided documents, including conceptual plans and previous investigations on the subject property.

• Engaged a subcontractor to advance eleven (11) test borings and install two (2) temporary monitoring wells within or very near the proposed building footprint.

• Observed and classified soil and rock samples recovered from the test borings, took groundwater level measurements, and prepared test boring logs.

• Engaged a testing laboratory to perform laboratory analyses on soil and rock core samples obtained from the test borings to verify visual classification and evaluate subsurface conditions.

• Developed preliminary geotechnical considerations for earthworks and building foundation design and construction.

• Prepared this Preliminary Geotechnical Report.

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The purpose of this study was to provide a preliminary assessment of soil and groundwater conditions and address geotechnical considerations for project planning. Additional explorations and geotechnical study by the design-build team will be required in a later phase of design to confirm or revise the general geotechnical considerations presented herein.

1.3 Authorization

Our work was performed in general accordance with our proposal dated May 23, 2025, and the resulting Standard Professional Services agreement executed July 3, 2025.

1.4 Vertical and Horizontal Reference

Borings were located and referenced on site using measurements to site features and handheld GPS with accuracy on the order of 5 to 10 feet. The locations shown on the attached figure should be considered approximate.

Elevations referenced in this report and on the attached test boring logs were estimated from a March 2025 site survey conducted by Martinez Couch & Associates.

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2. Site and Project Description

2.1 Site Description and History

The assemblage site slated for development is currently being utilized as a surface parking lot in downtown Hartford, Connecticut.

According to previous environmental reports prepared by others, the site was historically utilized for multiple commercial and residential purposes dating to at least 1885. All on-site buildings were demolished between 1986 and 1988, after which the property sat vacant until it was developed for surface parking in 2005.

The site gradually slopes downward to the south and east, with a total relief of about 15 feet within the proposed construction area.

2.2 Proposed Construction

The project is currently in the planning and conceptual design phase. We understand at this time that the project involves construction of a 9-story federal courthouse facility with one

(1) underground parking level.

Further details regarding site entry, grading, site utilities, and building construction have not yet been developed. For the purpose of this preliminary report, we have assumed that the underground parking level will either 1) coincide with Allyn Street grade and be constructed at (+/-) El. 36 ft. or 2) be embedded below Allyn Street grade at (+/-) El. 26 ft. Either option will require excavations and below-grade walls along the other three sides of the building footprint.

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3. Exploration Procedures

3.1 Test Borings

The boring locations were laid out on the site from the provided conceptual plan using handheld GPS and approximate measurements from site features. Borings were located in areas within or near the expected building footprint, as known at the time of investigation.

Approximate boring locations relative to the property boundary are shown on Figure 1.

Eleven (11) soil test borings (B-1 through B-11/MW-7) were performed at the site between

July 21 and August 4, 2025, by Seaboard Drilling, under subcontract to GEI. The appropriate one-call utility location service (Call Before You Dig) was contacted prior to our arrival. Each boring location within the site was also pre-scanned for utilities or other obstructions using geophysical methods. The borings were advanced to depths of 27 feet to

51 feet each, terminating either with sampler/roller bit refusal or a planned maximum depth, utilizing a combination of hollow-stem augering and drive and wash techniques using a truck-mounted drilling rig. Boring logs are attached in Appendix A.

Standard Penetration Testing (SPT) and split-spoon sampling were performed continuously through the upper 10 to 12 feet of the borings and at 5-foot intervals thereafter using a 140-pound automatic hammer. Two (2) undisturbed (tube) samples were collected from natural cohesive (silts/clays) soils for laboratory strength testing. Rock core sampling for a length of

4 to 10 feet was conducted within three (3) of the borings subsequent to drill refusal.

Representative samples of the soil and rock obtained by the borings were classified by the on-site GEI professional. With exception of the monitoring wells, all borings were backfilled with drill cuttings and patched using cold patch asphalt upon completion.

3.2 Monitoring Wells

Two (2) monitoring wells (MW-6 and MW-7) were installed to depths of 25.0 feet below existing grade at the approximate locations shown on Figure 1. Well MW-6 was installed directly adjacent to boring B-1 while boring MW-7 was installed in conjunction with boring

B-11. Monitoring well installation logs are attached in Appendix A.

3.3 Shear Wave Velocity Measurements

GEI retained Hager-Richter Geoscience to perform geophysical seismic field testing at the site on July 30, 2025. Surface-based shear wave velocity measurements were collected using

Multi-Channel Analysis of Surface Waves (MASW) method arrays. The MASW method measures the travel times of ambient (passive) vibrations to geophones mounted on the ground surface at incremental distances along an array. Shear wave velocity measurements were collected using the MASW method along three (3) profile lines within the site, as

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3.4 Geotechnical Laboratory Testing

Laboratory testing was performed on selected soil and rock samples collected during the exploration program to aid in classification and estimation of engineering properties. Tests performed by GeoTesting Express, under subcontract to GEI, included the following:

• One (1) organic content (ASTM D2974)

• Six (6) grain-size analysis with standard sieve set (ASTM D422)

• Six (6) moisture content analyses (ASTM D2216)

• Three (3) Atterberg limits (ASTM D4318)

• Two (2) consolidated undrained (C-U) triaxial compression (ASTM D4767)

• Two (2) unconfined compressive strength of rock (ASTM D7012C)

Results of the laboratory testing program are included in Appendix B.

3.5 Soil Corrosivity Testing

Soil corrosivity laboratory testing was performed by GeoTesting Express, Inc., under subcontract to GEI. Two (2) composite soil samples, one collected from samples obtained within the historic fill and one from samples collected within natural fine-grained soils, were tested for the following parameters

• pH (ASTM G51)

• Laboratory resistivity (ASTM G57)

• Chlorides (ASTM D512)

• Sulfates (ASTM D516)

Results of the corrosion laboratory testing are provided in Appendix B.

3.6 Previous Investigations

Several subsurface investigations have been performed on the property in recent years by others for purpose of environmental characterization. Data relevant to this evaluation has been excerpted and compiled in Appendix D for reference.

Historical subsurface data obtained by those other than GEI is provided for reference purposes only. We make no specific claim to its accuracy, and did not rely on this data solely for interpretation of conditions and geotechnical recommendations.

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4. Subsurface Conditions

4.1 Geologic Setting

As noted elsewhere in this report, this urban site has been developed over multiple iterations and is directly underlain by variable historic fills. Natural soils underlying the site consist predominantly of thinly layered (varved) glacio-lacustrine clay and silt deposits of the former

Lake Hitchcock, which once extended southward to Rocky Hill, Connecticut. The fine-grained soils, which are often soft in-place, are overlain by a thin terrace of alluvial silts and sands, which was likely deposited by meltwater streams as the lake drained and the glacier retreated upvalley. Varved clay deposits typically rest on top of a layer of dense, coarse-grained glacial till that covers the underlying bedrock surface. The final thickness of these deposits varies considerably due to large differences in bedrock elevations and variations in post deposition erosion.

Bedrock is mapped by Rodgers (1985) as Portland Arkose, described as reddish brown, fine to medium-grained, sedimentary rock containing quartz and feldspar.

4.2 Subsurface Conditions

The generalized subsurface conditions at the site are described below, in order of increasing depth. The subsurface conditions between boring locations may differ. The nature and extent of variations between the sampling points will not become evident until construction.

Surface Material – Borings were conducted within the current parking lot and encountered

2.5 to 5.0 inches of asphalt, generally placed directly on historic fill with exception of boring

B-1.

Historic Fill – Underlying the asphalt, all borings with exception of boring B-1 encountered variable historic fill to depths of about 2 feet to 12 feet below current grade. Thickness of historic fill will vary across the site depending on multiple factors such as the previous presence of basements, vaults, tanks, etc. and previous grading operations.

Recovered samples within the fill generally consisted of gravelly sand to silt with variable proportions of debris such as concrete, timber, brick, and asphalt. As evidenced by borings

B-7, B-10, and the historic environmental borings attached in Appendix D, pockets of heavy debris are present within the fill, generally concentrated on the southeast part of the site but potentially present elsewhere as well. There also appear to be buried concrete slabs, footings, etc. up to about 10 inches in thickness at various locations underlying the site, though they do not appear at this time to be widespread.

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Sandy Silt – Underlying the fill, the borings generally encountered an upper layer of sandy silt up to about 10 feet in thickness. Within the central to northern portions of the site, this layer was typically sampled as reddish brown sandy silt with about 20 percent sand and up to

5 percent fine gravel. Within the southeastern portion of the site, as evidenced by borings B-

5, B-7, B-10, and B-11, this layer was more evident of natural low-lying alluvial soils and often included organic staining and minor organic content (wood) as well as thin layering of silts and sandy silts.

Standard Penetration Test (SPT) N-values within these soils varied from 7 to 29 blows/foot, indicating firm to very stiff consistency.

Varved Clay Deposits – Glacial-lake varved (finely layered) deposits typical to the region were encountered in all borings with exception of B-5, B-7, and B-10, at thicknesses of up to

26 feet. These soils were most prevalent along the western side of the site, thinning out moving to the east. Recovered samples were typically characterized as relatively uniform low to medium-plasticity silty clay with less than 5 percent fine sand. Natural water contents in the varved clays ranged from 38 to 51 percent and were generally described as moist to wet during drilling.

Generally in this area and confirmed by many of the borings, these deposits include a relatively stiff upper “crust” typically on the order of 5 to 6 feet in thickness, quickly transitioning to soft and very soft materials.

SPT N-values in the varved deposits varied between 7 and 10 blows/foot in the upper crust, indicating firm to stiff consistency, to between 4 and 0 (weight of hammer) blows per foot at depth, indicating a soft to very soft consistency.

Glacial Till – Very dense glacial till was encountered in the borings at depths of 20 to 32 feet. Recovered samples ranged from well-graded sand and gravel to rock fragments likely indicative of cobbles or possibly small boulders lodged within the stratum. Drilling advancement into this layer generally coincided with a sharp increase in resistance (“rig chatter”) and, very often, a moderate to severe loss of drilling fluids within the coarse deposits. SPT N-values ranged from 18 blows/foot to in excess of 100 blows/foot, indicating medium dense to very dense conditions.

Weathered Rock – Based on the boring results, there appears to be a layer of highly weathered/decomposed rock generally up to about 5 feet in thickness between the Glacial

Till and Bedrock stratums. In boring B-5, a rock-laden zone above bedrock approximately

10 feet in thickness was encountered that may signify cobbles to small boulders in the glacial till, highly weathered rock with intact seams, or a combination of both.

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The transition into this material was noted by sharp increases in SPT N-value, difficulty in advancement of the drilling tools, and presence of decomposed rock fragments in the samples and drill cuttings.

Bedrock – Intact bedrock was encountered and sampled in Borings B-1, B-5 and B-10.

Recovered samples were described as reddish-brown medium strong to strong, fresh to slightly weathered Arkose (Sandstone). Rock Quality Designations (RQDs) ranged from 39 to 87 percent, indicating Poor to Good quality. Unconfined compressive strength testing of two rock core samples varied from 4,090 to 11,187 lb/in2 (psi).

Refusal Material – Drilling or sampler refusals were noted in some of the borings where rock core sampling was not conducted. Drilling refusal is defined as material that could not be penetrated with the drill rig equipment used on the project. Refusal of the drilling tools may have resulted from the presence of tight gravel/cobble beds, boulders or ledges of weathered rock, or continuous, relatively hard competent rock. Diamond core procedures would be necessary to assess the character and apparent strength of materials below refusal.

Based on our observations and expectations of bedrock depths and conditions, drill and sampler refusal depths within borings B-3, B-4, B-7, and B-8 likely represent weathered to sound bedrock. Within boring B-2, the noted sampler refusal is likely within the glacial till stratum.

4.3 Groundwater

Groundwater levels measured in the monitoring wells installed on site by GEI and previously by BL Companies ranged from El. +23.50 to El. +46.81 ft., as shown in Table 1. Locations of the previously installed monitoring wells can be found in the Appendix D documents.

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Table 1: Summary of Groundwater Measurements

Well ID Measured By Date Depth

(feet)

Elevation

(feet)

MW-1

BL Companies

01/07/2019 3.29 46.51

03/18/2019 2.99 46.81

GEI 08/06/2025 4.50 45.30

MW-2

BL Companies

01/07/2019 7.29 33.01

03/18/2019 6.63 33.67

GEI 08/06/2025 10.67 29.63

MW-3

BL Companies

01/07/2019 6.06 36.44

03/18/2019 5.72 36.78

GEI 08/06/2025 7.42 35.08

MW-4

BL Companies

01/07/2019 12.45 25.75

03/18/2019 12.29 25.91

GEI 08/06/2025 13.58 24.62

MW-5

BL Companies

01/07/2019 10.39 24.11

03/18/2019 9.74 24.76

GEI 08/06/2025 11.00 23.50

MW-6 GEI 08/06/2025 15.42 33.18

MW-7 GEI 08/06/2025 14.10 23.90

MW-101

BL Companies 03/18/2019 8.42 37.78

GEI 08/06/2025 9.67 36.53

MW-102

BL Companies 03/18/2019 8.96 25.04

GEI 08/06/2025 10.50 23.50

MW-103

BL Companies 03/18/2019 8.55 33.45

GEI 08/06/2025 11.50 30.50

The depth to the first wet sample within the borings is also noted on the boring logs, for additional reference. Formal groundwater measurements were not made in the borings due to the introduction of drilling fluids.

At most locations, the groundwater measurements coincide approximately with the lower few feet of historic fill. Along the western side of the site, groundwater was measured in the natural fine-grained deposits at variable depths. We note that the natural fine-grained deposits will likely exhibit very slow infiltration and recharge rates. Therefore, groundwater may be present within these soils but not observed as free water within excavations until several hours after the hole is opened.

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Groundwater levels should continue to be monitored in the wells, which are expected to be left in place, as construction approaches. Groundwater levels are expected to fluctuate with season, precipitation, temperature, construction activity in the area, and other factors. Based upon the measurements to date, seasonal groundwater fluctuation beneath the site appears to be on the order of 2 to 4 feet. Groundwater level measurements represent conditions at the times and locations when the measurements were made. Different groundwater elevations will occur at other times and locations.

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5. Design Considerations

5.1 General Suitability

The purpose of this investigation was to inform the design-build teams of general subsurface conditions at the site and any risks expected to have a significant impact on cost planning.

The geotechnical considerations provided herein are conceptual and are based on limited geotechnical data. Additional explorations and geotechnical study by the design-build team will be required in a later phase of design to confirm or revise these considerations, taking into account project-specific design attributes that are not yet developed and all regulatory requirements.

Based upon the investigations conducted to date, the key geotechnical considerations and risks associated with the proposed development include the following:

1. The presence of historic urban fill known to include debris of variable character and prevalence, and embedded concrete obstructions at certain locations.

2. The presence of groundwater requiring temporary and permanent controls, the extent of which largely depending on finished grade of the lower parking level.

3. Coarse natural deposits at depth of cobbles, small boulders, and/or weathered rock fragments known to cause loss of fluids when drilled through.

4. Very soft fine-grained deposits known to be slow-draining and highly susceptible to disturbance by construction equipment. The impact of this risk will also largely be determined by finished grade of the lower parking level.

5. Potential damage to nearby structures as the result of site construction.

The following potential subsurface risks, at minimum, should be further investigated by the design-build team as part of a final design test boring program:

1. The prevalence, extents, and characteristics of debris and obstructions within the historic fill.

2. Further confirmation on the depth to and quality of rock underlying the site, especially if drilled foundations are to be anchored into this material.

5.2 Foundation Support Options

The historic fills and underlying natural fine-grained soils are not suitable for directly supporting a structure of this scale directly on shallow foundations. Mitigations such as ground improvements or drilled deep foundations, as discussed in more detail below, will be required on this project.

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The eventual selection of foundation type will depend on several factors, including cost, constructability, performance thresholds (i.e. risk tolerance), and impacts to neighboring structures.

5.2.1 Ground Improvements

A ground improvement system consisting of aggregate piers or grouted rigid inclusions, as described in more detail below, designed and installed by a qualified, specialty design-build contractor, followed by construction of conventional shallow foundations and slab-on-grade appears to be a feasible alternative for support of the new building. The ground improvement specialty contractor, after review of the site data, will choose the proprietary pier and installation system best suited for site conditions.

Ground improvements should be designed and installed by a specialty geotechnical contractor and held to a performance specification that includes an allowable bearing pressure and maximum settlement. Based on experience with similar projects in similar geologic conditions, the specialty contractor will design a system intended to make effective use of reinforcing elements and meet the performance specifications. Particulars of the ground improvement program, including element type, length, diameter, spacing, etc., as well as that of the load transfer platform should be designed by the contractor’s Connecticut-licensed Professional Engineer. Performance of the designed ground improvements should be verified before the start of production installation by performing a suitable modulus test

(aggregate piers) or load test (grouted rigid inclusions).

As noted above, elevation of the lower-level parking slab is not known at this time. If the slab is embedded below Allyn Street, installing the ground improvement elements from lower-level grade will, subject to review of site logistics by the design-build team, likely be more efficient than from current grade. The majority of below-ground obstructions, such as any remnant walls or building piles, would be exposed and more readily apparent during installation by this sequence. The site general contractor will be responsible for providing a suitable work platform for heavy equipment access.

Even with prior excavation to lower-level grade, pre-drilling through historic fills should be expected and planned for.

The primary advantage of this option would be cost-effectiveness and the ability to utilize standard shallow foundations and grade slabs. Of environmental importance, these methods produce minimal spoils. Drawbacks would include potential difficulties with encountering obstructions and a need for lateral support from drilled elements, which these would not provide.

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5.2.2 Drilled Foundations

The use of drilled foundations in combination with pile caps and a structural slab also appears to be a feasible alternative for the structure. Subject to further review by the design-build team, this option would most likely involve micropiles socketed into rock. In this area, there are multiple qualified specialty micropile contractors and this is a relatively common foundation technique.

The specialty contractor is generally responsible for the final micropile design and installation methods based on a required capacity. Drilled micropiles should be designed and installed in accordance with all applicable Building Code provisions. One verification load test should be conducted for each size of micropile used on the project.

Though drilled caissons in excess of (+/-) 18 inches in diameter are technically feasible and would provide a large increase in lateral capacity, this method is not likely to be cost-effective for a structure of this scale. The pool of qualified local contractors is also smaller, relative to other pile types.

The primary advantage of drilled foundations would be added lateral capacity, should this be a requirement of structural design. This method would also be more effective in advancing past obstructions, though we do point out that natural coarse deposits caused issues with the test borings in terms of fluid loss, which should be expected and planned for if micropiles are used. Drawbacks would include cost and schedule impacts associated with construction of the pile caps and structural slab, along with management of contaminated drill spoils which may prove challenging.

5.2.3 Driven Foundations

We do not recommend the use of driven piles, due primarily to the potential for damage to neighboring structures.

5.3 Lower-level Floor Slab

The soils underlying the site are not suitable for direct support of slabs-on-grade. As such, the lower-level floor slab should either be supported by improved ground or designed as a structural slab supported on drilled foundations.

5.4 Seismic Design

The 2022 edition of the Connecticut Building Code document mirrors the 2021 International

Building Code, with exception of the revisions and supplemental information provided by state building officials.

The weighted-average shear wave velocities within the upper 100 feet of the subsurface profile, 𝑣̅𝑠100, at the locations tested varied between 1,473 to 1,653 feet per second, which is consistent with Site Class C.

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The Site Class was used in conjunction with the seismic hazard (SS, S1) for this location to determine spectral design values. Thick (> 10 feet) deposits of relatively soft clays were encountered at the site. However, our experience with the clays from this geologic formation along with recent strength testing at this site indicate that undrained shear strength (Su) is in excess of 500 lb/ft2. Site Class E thereby does not apply at this site.

Corresponding spectral response design parameters are as follows:

Table 2: Seismic Design Values

2022 Connecticut Building Code

Site Class C

SS 0.189 g

S1 0.055 g

SDS 0.164 g

SD1 0.055 g

PGAM 0.132 g

Seismic Design Category

(Risk Category I, II, III, or IV) A

We calculated the spectral response parameters for the site using general procedures outlined in the Building Code. Peak ground acceleration (PGAM) is adjusted for Site Class effects, per ASCE 7-16.

The seismic design factors given above correspond to Seismic Design Category A for Risk

Category I, II, III, or IV structures.

Soils underlying the site and proposed building are not considered susceptible to liquefaction or other seismic hazards.

5.5 Lateral Support

In addition to the lateral loads exerted by the soil against lower-level walls, allowance should be included for lateral stresses imposed by any temporary or long-term surcharge loads, such as construction equipment, vehicles adjacent to the walls, or adjacent footing loads. Design of basement walls should not incorporate the lateral support provided by any temporary shoring works that are used to facilitate excavation to the basement level.

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Positive wall drainage should be provided in general accordance with Section 5.6 for all below-grade earth retaining structures. Where backfill soils are not drained using an appropriately designed drainage system, the lateral soil pressure on proposed walls must consider hydrostatic forces and submerged soil unit weight.

Note the Connecticut Building Code does not require that below-grade walls at this level of site seismicity be designed to withstand seismic lateral pressures.

5.6 Foundation Drainage

Groundwater intrusion should be expected during excavation and installation of the below-grade parking level, the severity of which will depend on finished grades. Drainage and waterproofing measures intended to prevent hydrostatic pressures from developing on the foundation walls and below the lower-level floor slab should thus be incorporated into the building design.

Subject to further review and confirmation by the design-build team, these measures should include, at minimum, the following:

• Perimeter foundation drain

• Underslab drains embedded within the slab base

• Waterproofing materials and a prefabricated drainage board along the basement walls

• Backfill with well-draining material

• Vapor barrier beneath the lower-level floor slab, with waterproofing for spaces that extend below the slab such as mechanical pits or elevator pits

The foundation drains and underdrains should be preferably drained by gravity into an approved drainage system or by mechanical means with provisions for battery or generator backup during power outages.

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6. Construction Considerations

6.1 Subgrade Preparation

Based on the current plans, we expect initial site preparations will include excavations up to about 16 or 26 feet in depth, depending on finished grades, to construct the lower-level parking. The resulting subgrade is expected to consist of moist to saturated historic fills or fine-grained native soils.

The native fine-grained soils are slow to drain and highly susceptible to disturbance by construction equipment. Proceeding north and west into the hillside, the lower-level subgrade is expected to be very soft and wet. Installation of foundation elements will require a stable working platform for equipment to move on. Use of a suitable crushed stone working platform, or alternative means, to protect and maintain subgrade integrity should be expected and planned for.

6.2 Excavation and Shoring

Excavations can be accomplished with conventional earthmoving equipment. All excavations should be sloped or shored in accordance with the local, state, and federal regulations, including Occupational Safety and Health Agency (OSHA 29 CFR Part 1926) excavation trench safety standards.

Because of the depth of excavation for the lower level and the proximity of adjacent structures and roadways, temporary excavation support systems will be required for the project. A Connecticut-registered professional engineer engaged by the design-build team should design the excavation support system.

Drilled soldier-pile and lagging systems or soil-nail walls are likely suitable for use on this project. As the site was previously developed, below-grade obstructions such as previous foundations, debris, etc. may be encountered along areas of the excavation support. Pre-drilling to native soil should be expected if a soldier-pile and lagging wall is used. The use of soil-nail walls, while technically feasible, may be limited by 1) short-term stability of open cuts within the natural fine-grained soils and variable and debris-laden historic fills, 2) grout loss into debris-laden fills, and 3) encountering saturated soils at various levels. Design of soil nails or tie-back anchors, if needed, should take into account presence of utilities behind the walls.

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6.3 Dewatering

Dewatering during excavation to the lower parking level should be expected and planned for, the means and methods for which to be determined by the design-build team. Any dewatering should be performed in a manner that will prevent loosening or migration of the subgrade soils. Discharge of excavation dewatering fluids should comply with all applicable local, state, and federal regulations.

In general, based on the measurements to date, groundwater intrusion should be expected within the lower few feet of historic fills at a relatively high rate and within seams of the natural fine-grained deposits at a much slower rate. If the lower coarse-grained glacial till soils are encountered, intrusion at a relatively high rate would be expected.

6.4 Protection of Existing Structures

Th eastern side of the project excavation will be constructed in close proximity to masonry structures associated with the St. Patrick-St. Anthony church. There are also structures in proximity across Church Street and High Street. These structures may be affected by installation of ground improvement elements/drilled foundations or by temporary excavation support measures.

Vibration-reducing measures may be required for drilled elements installed in close proximity to the existing structures.

Prior to the start of construction, we recommend performing a pre-condition survey of all adjacent structures. During construction, particularly during excavation and installation of ground improvement piers/drilled piles or shoring elements in close proximity, we recommend monitoring the adjacent buildings using vibration monitors and crack gauges where necessary to detect movements as they occur.

6.5 Soil Re-use

Historic urban fills will likely not be suitable for re-use as backfill on the project due to their variable character and prevalence of debris. Natural fine-grained soils expected to be encountered during site excavations will also not be suitable for re-use as backfill due to high fines content and moisture susceptibility.

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7. Closure

7.1 Limitations

The purpose of this investigation was to inform the design-build teams of general subsurface conditions at the site and any risks expected to have a significant impact on cost planning.

The geotechnical considerations provided herein are conceptual and are based on limited geotechnical data. Additional explorations and geotechnical study by the design-build team will be required in a later phase of design to confirm or revise these considerations, taking into account project-specific design attributes that are not yet developed and all regulatory requirements. At minimum, this investigation should address the potential risk items listed in

Section 5.1.

Our professional services for this project have been performed in accordance with generally accepted engineering practices. No warranty, expressed or implied, is made.

GEI Consultants, Inc.

Figures

FIGURE NO.

GEI PROJECT NO: 2503909

TEST LOCATION PLAN

DOWNTOWN FEDERAL COURTHOUSE – ALLYN STREET SITE

HARTFORD, CT 1

LEGEND

APPROX. TEST BORING LOCATION

SOURCE:

CITY OF HARTFORD GIS

B-4

B-1

B-2

B-3

B-7

B-8

B-10

B-6

B-5

MW-6

B-11/MW-7

B-9

Appendix A

Boring and Monitoring Well Logs

F

IL

L S

A N

D Y

S

IL

T S

IL

T

Y C

L A

Y

4 in. ASPHALT

S1A (0"-12"): WIDELY GRADED SAND WITH GRAVEL (SW);

~60% F-C sand, ~35% F-C gravel, ~5% NP fines, reddish-brown, dry.

S1B (12"-17"): SANDY SILT (ML); ~75% NP fines, ~20% F-M sand, ~5% F-C gravel, reddish-brown, dry.

S2: Similar to S1B.

S3: Similar to S1B, stratified.

S4: Similar to S3.

S5: Similar to S3.

S6: SILTY CLAY (CL); 99.9% LP-MP fines, 0.1% F-sand, reddish-brown, stratified, wet.

PID = 0.1

PID = 0.2

PID = 0.1

PID = 0.0

PID = 0.1

S1

S2

S3

S4

S5

S6

24/17

24/21

24/20

24/18

24/16

24/24

9-4-5-4

4-7-9-9

10-13- 16-16

9-11-13-

7-9-8-11

WOH-

WOH-1-

0.3 to 2.3

2.3 to 4.3

4.3 to 6.3

6.3 to 8.3

8.3 to

10.3 to

U = Undisturbed Sample

SC = Sonic Core

DP = Direct Push Sample

HSA = Hollow-Stem Auger

TOTAL DEPTH (ft): 48.0

RQD = Rock Quality Designation = Length of Sound Cores>4 in / Pen.,%

HAMMER TYPE: Automatic

ABBREVIATIONS:

DRILLING INFORMATION

LOGGED BY: B. Flood

AUGER I.D./O.D.: 4.25 inch / NA

Qp = Pocket Penetrometer Strength

I.D./O.D. = Inside Diameter/Outside Diameter

B-1

Sv = Pocket Torvane Shear Strength

PI = Plasticity Index

NA, NM = Not Applicable, Not Measured

Blows per 6 in.: 140-lb hammer falling

30 inches to drive a 2-inch-O.D.

split spoon sampler.

CASING I.D./O.D.: 4 inch/ NA

CORE BARREL I.D./O.D. NA / NADRILL ROD O.D.: NM

WATER LEVEL DEPTHS (ft): 15.0 7/23/2025 First wet sample.

CORE BARREL TYPE:

WOR = Weight of Rods

WOH = Weight of Hammer

DRILLING METHOD: Hollow Stem Auger/Drill and wash

LL = Liquid Limit

PID = Photoionization Detector

Pen. = Penetration Length

Rec. = Recovery Length

BORING INFORMATION

DRILLER NAME: J. Nitsch/D. Griffin

C = Core Sample

S = Split Spoon Sample

RIG TYPE:

Depth (ft)

Elev.

(ft)

L a y e r

N a m e

Soil and Rock Description Drilling Remarks/ Field Test DataSample

No.

Pen./ Rec.

(in)

Blows per 6 in.

or RQD

Depth (ft)

Sample Information

BORING

VERTICAL DATUM:

GROUND SURFACE EL. (ft): 49

LOCATION: See plan.

DATE START/END: 7/23/2025 - 7/24/2025

DRILLING COMPANY: Seaboard

GEI PROJECT NUMBER: 2503909

PROJECT NAME: Hartford Federal Courthouse

CITY/STATE: Hartford, Connecticut

NOTES:

G

E I

W O

B U

R N

S T

D

-L O

C A

T

IO

N -L

A Y

E R

N A

M E

H

R

T F

O R

D F

E D

E R

A L

C O

U R

T H

O U

S E

G

IN

T .G

P J

G

I D

A T

A T

E M

P L

A T

E

.G

D T

/5 /2

S

T Y

C L A

Y G

L A

C

IA

L T

IL

L

B E

D R

O C

K

S7: Similar to S6.

S8: Similar to S6.

S9A (0"-22"): Similar to S6.

S9B (22"-24"): SILTY SAND WITH GRAVEL (SM); ~50% F-C

sand, ~30% F-C gravel, ~20% NP fines, reddish-brown, wet.

S10: WIDELY GRADED SAND WITH SILT AND GRAVEL

(SW-SM); ~60% F-C sand, ~30% F-C gravel, ~10% NP fines, reddish-brown, wet.

C1: SANDSTONE/ARKOSE; reddish-brown, medium strong to strong, fine-grained, slightly weathered, close to moderately close joints at 0-40 degrees.

Core times: 14.5, 15.75, 17.75, 13.5, 9.0 min/ft

S7

S8

S9

S10

C1

24/23

24/22

24/24

11/11

60/46

WOH-

WOH-

WOH-1

WOH-

WOH-

WOH-

WOH

WOH-

WOH-

WOH-4

24-50/5" to to to to

35.9 to

B-1

Depth (ft)

Elev.

(ft)

L a y e r

N a m e

Soil and Rock Description Drilling Remarks/ Field Test DataSample

No.

Pen./ Rec.

(in)

Blows per 6 in.

or RQD

Depth (ft)

Sample Information

BORING

VERTICAL DATUM:

GROUND SURFACE EL. (ft): 49

LOCATION: See plan.

DATE START/END: 7/23/2025 - 7/24/2025

DRILLING COMPANY: Seaboard

GEI PROJECT NUMBER: 2503909

PROJECT NAME: Hartford Federal Courthouse

CITY/STATE: Hartford, Connecticut

NOTES:

G

E I

W O

B U

R N

S T

D

-L O

C A

T

IO

N -L

A Y

E R

N A

R

T F

O R

D F

E D

E R

A L

C O

U R

T H

O U

S E

G

IN

T .G

I D

A T

A T

E M

P L

A T

E

.G

B

D R

O C

K

C2: SANDSTONE/ARKOSE; reddish-brown, medium strong to strong, fine-grained, fresh to slightly weathered, close to moderately close joints at 0-40 degrees. Core times: 7.5, 9.0, 9.0, 12.25, 10.25 min/ft.

Planned Extent.

Backfilled with drill cuttings.

C2 60/56 8243 to

B-1

Depth (ft)

Elev.

(ft)

-10

L a y e r

N a m e

Soil and Rock Description Drilling Remarks/ Field Test DataSample

No.

Pen./ Rec.

(in)

Blows per 6 in.

or RQD

Depth (ft)

Sample Information

BORING

VERTICAL DATUM:

GROUND SURFACE EL. (ft): 49

LOCATION: See plan.

DATE START/END: 7/23/2025 - 7/24/2025

DRILLING COMPANY: Seaboard

GEI PROJECT NUMBER: 2503909

PROJECT NAME: Hartford Federal Courthouse

CITY/STATE: Hartford, Connecticut

NOTES:

G

E I

W O

B U

R N

S T

D

-L O

C A

T

IO

N -L

A Y

E R

N A

R

T F

O R

D F

E D

E R

A L

C O

U R

T H

O U

S E

G

IN

T .G

I D

A T

A T

E M

P L

A T

E

.G

L S

IL

T

S

IL

T Y

C L A

Y

4 in. ASPHALT

S1: WIDELY GRADED SAND WITH SILT AND GRAVEL

(SW-SM); ~50% F-C sand, ~40% F-C gravel, ~10% NP fines, brown, dry.

S2: Similar to S1.

S3: Poor recovery. Brick in sampler.

S4: WIDELY GRADED GRAVEL WITH SAND (GW); ~70% F-C

gravel, ~30% F-C sand, brown, dry, with brick fragments.

S5A (0-20"): Similar to S4.

S5B (20-22"): SANDY SILT (ML); ~80% NP fines,~ 20% F-sand, reddish-brown, dry.

S6: SILTY CLAY (CL); 99.7% LP-MP fines, 0.3% F-sand, reddish-brown, stratified, wet.

S7: Similar to S6.

PID = 0.0

PID = 0.0

PID = 0.0

PID = N/A

PID = N/A

S1

S2

S3

S4

S5

S6

S7

24/14

24/9

15/1

24/12

24/9

24/22

24/24

12-26- 10-5

4-6-4-8

8-11- 50/3

9-7-5-5

4-5-5-5

4-5-5-6

2-1-1-1

0.3 to 2.3

2.3 to 4.3

4.3 to 5.6

6.3 to 8.3

8.3 to

10.3

10.3 to

12.3 to

U = Undisturbed Sample

SC = Sonic Core

DP = Direct Push Sample

HSA = Hollow-Stem Auger

TOTAL DEPTH (ft): 31.8

RQD = Rock Quality Designation = Length of Sound Cores>4 in / Pen.,%

HAMMER TYPE: Automatic

ABBREVIATIONS:

DRILLING INFORMATION

LOGGED BY: B. Flood

AUGER I.D./O.D.: 4.25 inch / NA

Qp = Pocket Penetrometer Strength

I.D./O.D. = Inside Diameter/Outside Diameter

B-2

Sv = Pocket Torvane Shear Strength

PI = Plasticity Index

NA, NM = Not Applicable, Not Measured

Blows per 6 in.: 140-lb hammer falling

30 inches to drive a 2-inch-O.D.

split spoon sampler.

CASING I.D./O.D.: 4 inch/ NA

CORE BARREL I.D./O.D. NA / NADRILL ROD O.D.: NM

WATER LEVEL DEPTHS (ft): 10.0 7/23/2025 First wet sample.

CORE BARREL TYPE:

WOR = Weight of Rods

WOH = Weight of Hammer

DRILLING METHOD: Hollow Stem Auger/Drill and wash

LL = Liquid Limit

PID = Photoionization Detector

Pen. = Penetration Length

Rec. = Recovery Length

BORING INFORMATION

DRILLER NAME: J. Nitsch/N. Kern

C = Core Sample

S = Split Spoon Sample

RIG TYPE:

Depth (ft)

Elev.

(ft)

L a y e r

N a m e

Soil and Rock Description Drilling Remarks/ Field Test DataSample

No.

Pen./ Rec.

(in)

Blows per 6 in.

or RQD

Depth (ft)

Sample Information

BORING

VERTICAL DATUM:

GROUND SURFACE EL. (ft): 45

LOCATION: See plan.

DATE START/END: 7/23/2025 - 7/25/2025

DRILLING COMPANY: Seaboard

GEI PROJECT NUMBER: 2503909

PROJECT NAME: Hartford Federal Courthouse

CITY/STATE: Hartford, Connecticut

NOTES:

G

E I

W O

B U

R N

S T

D

-L O

C A

T

IO

N -L

A Y

E R

N A

R

T F

O R

D F

E D

E R

A L

C O

U R

T H

O U

S E

G

IN

T .G

I D

A T

A T

E M

P L

A T

E

.G

T Y

C L A

Y G

L A

C

IA

L T

IL

L

Undisturbed sample

S8: Similar to S6.

S9: Similar to S6.

S10: WIDELY GRADED SAND WITH GRAVEL (SW); ~60%

F-C sand, ~35% F-C gravel, ~5% NP fines, reddish-brown, wet.

Sampler refusal at 31.8 ft.

Backfilled with drill cuttings.

Rig chattering at 28 ft.

T1

S8

S9

S10

24/20

24/24

22/10

WOH-

WOH-1-

WOH-

WOH-

WOH-

WOH

9-10-27- 50/4" to to to to

31.8

B-2

Depth (ft)

Elev.

(ft)

L a y e r

N a m e

Soil and Rock Description Drilling Remarks/ Field Test DataSample

No.

Pen./ Rec.

(in)

Blows per 6 in.

or RQD

Depth (ft)

Sample Information

BORING

VERTICAL DATUM:

GROUND SURFACE EL. (ft): 45

LOCATION: See plan.

DATE START/END: 7/23/2025 - 7/25/2025

DRILLING COMPANY: Seaboard

GEI PROJECT NUMBER: 2503909

PROJECT NAME: Hartford Federal Courthouse

CITY/STATE: Hartford, Connecticut

NOTES:

G

E I

W O

B U

R N

S T

D

-L O

C A

T

IO

N -L

A Y

E R

N A

R

T F

O R

D F

E D

E R

A L

C O

U R

T H

O U

S E

G

IN

T .G

I D

A T

A T

E M

P L

A T

E

.G

L S

A N

D Y

S

IL

T

4 in. ASPHALT S1: SILTY SAND WITH GRAVEL (SM); ~50% F-C sand, ~30% NP fines, ~20% F-C gravel, reddish brown, moist, with asphalt and brick fragments.

S2: SILT WITH SAND AND GRAVEL (ML); ~60% LP-MP Fines, ~25% F-C Gravel, ~15% F-C Sand, reddish brown, moist, with brick fragments.

S3: SANDY SILT (ML); ~70% LP-MP fines, ~20% F-C sand, ~10% F- gravel, brown, moist, with brick fragments.

S4: Similar to S3. Brick fragments, few organic fibers.

S5: Similar to S3. Asphalt and brick fragments.

S6: SANDY SILT (ML); ~80% LP fines, ~20% F-M sand, stratified, brown, moist.

PID = 0.5

PID = 1.5

PID = 1.2

PID = 3.0

PID = 0.1

S1

S2

S3

S4

S5

S6

24/21

24/16

24/16

24/24

24/21

24/15

7-8-22-

7-7-8-6

3-3-3-3

1-2-2-1

2-2-4-3

6-7-10-

0.3 to 2.3

2.3 to 4.3

4.3 to 6.3

6.3 to 8.3

8.3 to

10.3 to

U = Undisturbed Sample

SC = Sonic Core

DP = Direct Push Sample

HSA = Hollow-Stem Auger

TOTAL DEPTH (ft): 39.5

RQD = Rock Quality Designation = Length of Sound Cores>4 in / Pen.,%

HAMMER TYPE: Automatic

ABBREVIATIONS:

DRILLING INFORMATION

LOGGED BY: T. Rezzani

AUGER I.D./O.D.: 4.25 inch / NA

Qp = Pocket Penetrometer Strength

I.D./O.D. = Inside Diameter/Outside Diameter

B-3

Sv = Pocket Torvane Shear Strength

PI = Plasticity Index

NA, NM = Not Applicable, Not Measured

Blows per 6 in.: 140-lb hammer falling

30 inches to drive a 2-inch-O.D.

split spoon sampler.

CASING I.D./O.D.: 4 inch/ NA

CORE BARREL I.D./O.D. NA / NADRILL ROD O.D.: NM

WATER LEVEL DEPTHS (ft): 20.0 7/21/2025 First wet sample.

CORE BARREL TYPE:

WOR = Weight of Rods

WOH = Weight of Hammer

DRILLING METHOD: Hollow Stem Auger/Drill and wash

LL = Liquid Limit

PID = Photoionization Detector

Pen. = Penetration Length

Rec. = Recovery Length

BORING INFORMATION

DRILLER NAME: J. Nitsch

C = Core Sample

S = Split Spoon Sample

RIG TYPE:

Depth (ft)

Elev.

(ft)

L a y e r

N a m e

Soil and Rock Description Drilling Remarks/ Field Test DataSample

No.

Pen./ Rec.

(in)

Blows per 6 in.

or RQD

Depth (ft)

Sample Information

BORING

VERTICAL DATUM:

GROUND SURFACE EL. (ft): 42

LOCATION: See plan.

DATE START/END: 7/21/2025 - 7/21/2025

DRILLING COMPANY: Seaboard

GEI PROJECT NUMBER: 2503909

PROJECT NAME: Hartford Federal Courthouse

CITY/STATE: Hartford, Connecticut

NOTES:

G

E I

W O

B U

R N

S T

D

-L O

C A

T

IO

N -L

A Y

E R

N A

R

T F

O R

D F

E D

E R

A L

C O

U R

T H

O U

S E

G

IN

T .G

I D

A T

A T

E M

P L

A T

E

.G

T Y

C L A

Y G

L A

C

IA

L T

IL

L

S7: SILTY CLAY (CL); ~100% MP fines, reddish brown, stratified, wet.

S8: SANDY SILT WITH GRAVEL (ML); ~60% NP fines, ~25% F-C sand, ~15% F-C gravel, reddish brown, wet.

S9: SILTY SAND WITH GRAVEL (SM); ~40% NP fines, ~30% F-C sand, ~30% F-C gravel, reddish brown, wet.

S10: Similar to S9.

Drill refusal at 39.5 ft.

Backfilled with drill cuttings.

Rig chattering at 28 ft.

Rig chattering at 29 ft.

Rig chattering at 31 ft.

Heavy rig chattering at 36 ft.

S7

S8

S9

S10

24/24

24/11

24/17

9/7

WOH-1-

1-1

4-2-4-9

34-39- 49-39

26-50/3 to to to to

35.8

B-3

Depth (ft)

Elev.

(ft)

L a y e r

N a m e

Soil and Rock Description Drilling Remarks/ Field Test DataSample

No.

Pen./ Rec.

(in)

Blows per 6 in.

or RQD

Depth (ft)

Sample Information

BORING

VERTICAL DATUM:

GROUND SURFACE EL. (ft): 42

LOCATION: See plan.

DATE START/END: 7/21/2025 - 7/21/2025

DRILLING COMPANY: Seaboard

GEI PROJECT NUMBER: 2503909

PROJECT NAME: Hartford Federal Courthouse

CITY/STATE: Hartford, Connecticut

NOTES:

G

E I

W O

B U

R N

S T

D

-L O

C A

T

IO

N -L

A Y

E R

N A

R

T F

O R

D F

E D

E R

A L

C O

U R

T H

O U

S E

G

IN

T .G

I D

A T

A T

E M

P L

A T

E

.G

L S

A N

D Y

S

IL

T S

IL

T

Y C

L A

Y

3 in. ASPHALT

S1: WIDELY GRADED SAND WITH SILT AND GRAVEL

(SW-SM); ~70% F-C sand, ~20% F-C gravel, ~10% NP fines, brown, dry, with brick and concrete fragments.

S2: WIDELY GRADED SAND WITH SILT (SW-SM); ~80% F-C

sand, ~10% F-C gravel, ~10% NP fines, brown, dry, with brick, wood and concrete fragments.

S3: Similar to S2.

S4: SANDY SILT (ML); ~80% NP-LP fines, ~20% F- sand, reddish-brown, wet.

S5: SILTY CLAY (CL); 96.8% LP-MP fines, 2.1% F- sand, 1.1% F- gravel, reddish-brown, stratified, wet.

S6: Similar to S5.

PID = 0.0

PID = 0.0

PID = 0.0

PID = 0.0

PID = 0.0

S1

S2

S3

S4

S5

S6

24/15

24/10

24/9

24/19

24/24

24/24

10-9-5-7

5-5-6-6

9-44-9-7

4-4-5-5

3-4-3-4

2-2-2-2

0.3 to 2.3

2.3 to 4.3

4.3 to 6.3

6.3 to 8.3

8.3 to

10.3 to

U = Undisturbed Sample

SC = Sonic Core

DP = Direct Push Sample

HSA = Hollow-Stem Auger

TOTAL DEPTH (ft): 33.6

RQD = Rock Quality Designation = Length of Sound Cores>4 in / Pen.,%

HAMMER TYPE: Automatic

ABBREVIATIONS:

DRILLING INFORMATION

LOGGED BY: B. Flood

AUGER I.D./O.D.: 4.25 inch / NA

Qp = Pocket Penetrometer Strength

I.D./O.D. = Inside Diameter/Outside Diameter

B-4

Sv = Pocket Torvane Shear Strength

PI = Plasticity Index

NA, NM = Not Applicable, Not Measured

Blows per 6 in.: 140-lb hammer falling

30 inches to drive a 2-inch-O.D.

split spoon sampler.

CASING I.D./O.D.: 4 inch/ NA

CORE BARREL I.D./O.D. NA / NADRILL ROD O.D.: NM

WATER LEVEL DEPTHS (ft): 6.0 8/4/2025 First wet sample.

CORE BARREL TYPE:

WOR = Weight of Rods

WOH = Weight of Hammer

DRILLING METHOD: Hollow Stem Auger/Drill and wash

LL = Liquid Limit

PID = Photoionization Detector

Pen. = Penetration Length

Rec. = Recovery Length

BORING INFORMATION

DRILLER NAME: J. Nitsch

C = Core Sample

S = Split Spoon Sample

RIG TYPE:

Depth (ft)

Elev.

(ft)

L a y e r

N a m e

Soil and Rock Description Drilling Remarks/ Field Test DataSample

No.

Pen./ Rec.

(in)

Blows per 6 in.

or RQD

Depth (ft)

Sample Information

BORING

VERTICAL DATUM:

GROUND SURFACE EL. (ft): 46

LOCATION: See plan.

DATE START/END: 8/4/2025 - 8/4/2025

DRILLING COMPANY: Seaboard

GEI PROJECT NUMBER: 2503909

PROJECT NAME: Hartford Federal Courthouse

CITY/STATE: Hartford, Connecticut

NOTES:

G

E I

W O

B U

R N

S T

D

-L O

C A

T

IO

N -L

A Y

E R

N A

R

T F

O R

D F

E D

E R

A L

C O

U R

T H

O U

S E

G

IN

T .G

I D

A T

A T

E M

P L

A T

E

.G

T Y

C L A

Y G

L A

C

IA

L T

IL

L

S7: Similar to S5.

S8: Similar to S5.

S9: No sample recovery.

S10: Weathered rock fragments in tip of sampler.

Drill refusal at 33.5 ft.

Backfilled with drill cuttings.

Harder drilling noted at 32 ft.

S7

S8

S9

S10

24/24

24/24

24/0

1/0

WOH-

WOH-

WOH-

WOH

WOH-

WOH-

WOH-

WOH

WOH-

WOH-1-

50/1 to to to

33.5 to

33.6

B-4

Depth (ft)

Elev.

(ft)

L a y e r

N a m e

Soil and Rock Description Drilling Remarks/ Field Test DataSample

No.

Pen./ Rec.

(in)

Blows per 6 in.

or RQD

Depth (ft)

Sample Information

BORING

VERTICAL DATUM:

GROUND SURFACE EL. (ft): 46

LOCATION: See plan.

DATE START/END: 8/4/2025 - 8/4/2025

DRILLING COMPANY: Seaboard

GEI PROJECT NUMBER: 2503909

PROJECT NAME: Hartford Federal Courthouse

CITY/STATE: Hartford, Connecticut

NOTES:

G

E I

W O

B U

R N

S T

D

-L O

C A

T

IO

N -L

A Y

E R

N A

R

T F

O R

D F

E D

E R

A L

C O

U R

T H

O U

S E

G

IN

T .G

I D

A T

A T

E M

P L

A T

E

.G

L S

A N

D Y

S

IL

T

5 in. ASPHALT

S1B (5-13"): SILTY GRAVEL WITH SAND (GM); ~50% F-C

gravel, ~30% F-C sand, ~20% NP fines, gray and reddish brown, dry, with asphalt and brick fragments.

S2: SILTY SAND WITH GRAVEL (SM); ~60% F-C sand, ~25% NP fines, ~15% F-C gravel, brown to dark gray, moist, with brick fragments.

S3: SANDY SILT WITH GRAVEL (ML); ~70% LP-MP fines, ~15% F-C sand, ~15% F-C gravel, brown, moist, with asphalt and brick fragments.

S4: Similar to S3.

S5: SANDY SILT (ML); ~80% LP-MP fines, ~15% F-C sand, ~5% F gravel, dark gray, moist, with asphalt and brick fragments.

S6: SILT WITH SAND (ML); ~85% LP fines, ~15% F- sand, gray, wet, wood fragment in sampler.

PID = 1.0

PID = 0.9

PID = 0.2

Slow casing advancement at 6 ft.

PID = 0.1

PID = 59.0

S1

S2

S3

S4

S5

S6

24/13

24/10

24/18

24/11