Geotechnical_Report.pdf

16 OLD FORGE ROAD

SUITE A

ROCKY HILL, CT 06067

860.726.7889 whitestoneassoc.com

Office Locations:

NEW JERSEY PENNSYLVANIA MASSACHUSETTS CONNECTICUT FLORIDA NEW HAMPSHIRE NEW YORK

April 10, 2024 via email

NEW ENGLAND BORING CONTRACTORS

129 Kreiger Lane

Glastonbury, Connecticut 06033

Attention: Mr. Steven Preli Connecticut Manager

Regarding: LIMITED GEOTECHNICAL INVESTIGATION

PROPOSED COMMUNICATIONS TOWER

HERCULES DRIVE

MANCHESTER, HARTFORD COUNTY, CONNECTICUT

WHITESTONE PROJECT NO.: GM2421632.000

Dear Mr. Preli:

Whitestone Associates, Inc. (Whitestone) has completed a limited geotechnical investigation at the above-referenced site. The purpose of the investigation was to assess subsurface conditions for the proposed communications tower. Recommendations for support of the proposed communications tower and anticipated earthwork requirements are included herein.

1.0 PROJECT DESCRIPTION

1.1 Site Location & Existing Conditions

The subject property, located approximately 800 feet south of Hercules Drive, in the Town of

Manchester, Hartford County, Connecticut, currently is wooded and undeveloped.

1.2 Site Geology

Based on a review of the Surficial Materials Map of Connecticut (1992), the natural site soils consist of glacial till. The Bedrock Geologic Map of Connecticut (1985) indicates that the subject property is underlain by Lower Jurassic-age Portland Arkose, consisting of arkose and siltstone with minor conglomerate and shale, part of Central Lowlands; Newark Terrane - Hartford and Pomperaug Mesozoic Basins.

1.3 Proposed Construction

The proposed construction consists of erecting a self-supporting communications tower approximately

180 feet high for the purpose of this report, Whitestone assumes base foundation loads will be less than

50-kips axial, 50-kips shear, and 4,000 foot-kips overturning moment.

New England Boring Contractors

Limited Geotechnical Investigation

Hercules Drive

Manchester, Connecticut

Environmental & Geotechnical Engineers & Consultants

2.0 FIELD INVESTIGATION

Field exploration for the proposed communications tower consisted of advancing three borings (identified as B-1, B-2, and B-3) using an all-terrain vehicle (ATV) mounted Mobile B-53 drill rig equipped with hollow stem augers. The borings were backfilled with excavated soils generated from the investigation.

The locations of the borings are shown on the accompanying Boring Location Plan included as Figure 1.

The Records of Subsurface Exploration are provided in Appendix A.

The subsurface tests were conducted in the presence of a Whitestone engineer who observed field tests, recorded visual classifications, and collected samples of the various strata encountered. The tests were located in the field using normal taping procedures and estimated right angles. These locations are presumed to be accurate within a few feet.

The borings and Standard Penetration Tests (SPTs) were conducted in general accordance with ASTM International (ASTM) designation D1586. The SPT resistance value (N) can be used as an indicator of the consistency of fine-grained soils and the relative density of coarse-grained soils. The N-value for various soil types can be correlated with the engineering behavior of earthworks and foundations. Rock was cored using a NQ2-sized diamond bit. The rock core description, recovery, RQD, and other pertinent information were recorded on the boring log and are included in Appendix A on the Records of Subsurface Exploration. The RQD value reflects the quality and fracture spacing of the rock and is calculated by summing all unbroken samples that are four inches or longer divided by the total length of the run. The percentage of core recovery and RQD value provide an understanding of the physical and engineering properties of the rock.

Groundwater level observations, where encountered, were recorded during and immediately after the completion of field operations prior to backfilling the tests. Seasonal variations, temperature effects, man-made effects, and recent rainfall conditions may influence the levels of the groundwater, and the observed levels will depend on the permeability of the soils. Groundwater elevations derived from sources other than seasonally observed groundwater monitor wells may not be representative of true groundwater levels.

3.0 SUBSURFACE CONDITIONS

The subsurface soil conditions encountered within the subsurface tests conducted by Whitestone consisted of the following generalized strata in order of increasing depth. The Records of Subsurface Exploration are provided in Appendix A.

Surface Cover Materials: The borings encountered approximately four inches to six inches of topsoil at the ground surface, Glacial Till: Beneath the surface cover materials, the borings encountered glacial till, consisting of brown, medium dense to dense, silty sand with gravel, cobbles (USCS: SM). The SPT N-values within the glacial till ranged from 10 blows per foot (bpf) to 32 bpf. The glacial till extended to depths of 2.5 fbgs to five fbgs.

Bedrock: Boring B-1 encountered auger refusal on bedrock at a depth of five fbgs. Borings B-2 and B-3 encountered weathered bedrock at depths of 2.5 fbgs and five fbgs, respectively, and auger refusal on more competent bedrock at depths of three fbgs and six fbgs. The bedrock, which was cored in boring B- 1 from five fbgs to 15 fbgs, consisted of gray, moderately weathered, coarse to very coarse grained, hard, sandstone and conglomerate. Rock core recovery was 60 percent. The RQD values were nine percent and 20 percent, implying “very poor” rock quality.

Hercules Drive Manchester, Connecticut

Groundwater: Groundwater was not encountered in the borings. The groundwater level should be expected to fluctuate seasonally and following periods of precipitation and may perch over the dense glacial till or bedrock surface.

4.0 CONCLUSIONS & RECOMMENDATIONS

The tower may be supported on shallow foundations bearing within the glacial till or structural fill placed over the glacial till or bearing on a layer of crushed stone placed over the bedrock. The following recommendations have been developed on the basis of the previously described project characteristics and subsurface conditions encountered within the limited exploration conducted.

If there are any significant changes to the project characteristics or if significantly different subsurface conditions are encountered during construction, Whitestone should be consulted, so that the recommendations of this report can be reviewed.

4.1 Site Preparation & Earthwork

Surface Cover Stripping: Prior to stripping operations, any utilities should be identified and secured.

Vegetation, trees, shrubs, and other organic matter should be removed from within and at least five feet beyond the limits of the proposed structure footprint, as well as any other area that will require controlled structural fill placement. Tree/shrub removal should include the removal of stumps and root material.

Root structures will require removal in excess of the few inches of topsoil typically encountered at the ground surface. The contractor should be required to conduct earthwork in accordance with the recommendations in this report, including backfilling any excavation, etc. with structural fill.

Excavation Difficulties: The dense glacial till, which includes boulders, and shallow bedrock will present excavation difficulties. The bedrock surface typically undulates and may be encountered at shallower depths than in the borings. Excavation difficulties will be affected by excavation size and depth. The speed and ease of excavation also will depend on the type of equipment used and the skill of the operator. Boulders in the glacial till and the upper couple of feet of fractured/weathered bedrock can likely be broken up with the “hoe-ram” and removed with a large excavator. However, removal of bedrock below the upper couple of feet of weathered and fractured rock will require more effort.

Bedrock Subgrade Preparation: In foundation excavations, the bedrock surface from which the tower will derive support should not be steeper than 4:1 (horizontal:vertical). Exposed bedrock subgrade surfaces steeper than 4:1 (horizontal:vertical) should be stepped. Loose bedrock should be removed from the subgrade prior to placement. Bedrock fractures and joints should be tight. Bedrock joints, fractures, or fissures greater than 0.5 inches in width should be filled with lean concrete. Only minus 0.375-inch crushed stone should be placed directly over the bedrock. Structural fill (sand and gravel) should not be placed directly on the bedrock surface to reduce the likelihood of migration of fines into the bedrock.

Surface Preparation: Before placing fill materials to raise or restore grades to the desired subgrade elevations, the existing exposed soils should be compacted to a firm surface with several passes of a heavy plate compactor. The geotechnical engineer should identify soft or loose pockets that may require removal and replacement, or further evaluation. Should construction be started during the winter months, Whitestone should be contacted for alternate surface preparation procedures. Fill or backfill should be placed and compacted in accordance with the recommendations in this report.

Hercules Drive

Manchester, Connecticut

Weather Performance Criteria: The glacial till is moisture sensitive and will soften when exposed to water. Every effort should be made to maintain drainage of surface water runoff away from construction areas by grading and limiting the exposure of excavations and prepared subgrades to rainfall.

Accordingly, excavation and fill placement procedures should be conducted during favorable weather conditions. Overexcavation of wet or disturbed soils and replacement with controlled structural fill may be required prior to resuming work on subgrade soils.

Subgrade Protection & Maintenance: The glacial till is moisture sensitive and will degrade if exposed to inclement weather, freeze-thaw cycles, or repeated construction traffic. However, if properly protected and maintained as recommended herein, the site soils will provide adequate support for the proposed construction. The site contractors should employ appropriate means and methods to protect the subgrade including, but not limited to, the following:

► sealing exposed subgrade soils on a daily basis with a smooth drum roller operated in static mode;

► regrading the site as needed to maintain positive drainage away from open earthwork construction areas and to prevent standing water;

► removing wet surficial soils and ruts immediately; and

► limiting exposure to construction traffic and precipitation especially following inclement weather and subgrade thawing.

4.2 Structural Fill & Backfill

Imported Fill Material: Only minus 0.375-inch crushed stone should be placed directly over bedrock, Elsewhere, imported material placed as structural fill or backfill to restore design grades should consist of clean, relatively well-graded sand or gravel with a maximum particle size of three inches and up to 15 percent, by weight, of material finer than a #200 sieve. Imported material should be free of silt, clay, organics, and deleterious material. Imported material should be approved by a qualified geotechnical engineer prior to delivery to the site.

On-Site Material/Reuse: Whitestone anticipates that portions of the glacial till will be suitable for selective reuse as structural fill/backfill material, provided that soil moisture contents are controlled within three percent of optimum moisture level, particles larger than three inches in diameter are either removed or crushed, and objectionable portions, such as organics and deleterious material, are segregated.

Reuse of the site materials will be contingent on careful review in the field by the owner’s geotechnical engineer.

Submerged Fill: In the wet (flooding, perched water, or groundwater), consideration should be given to placing an open-graded, 0.75-inch crushed stone to provide a working mat, expedite dewatering efforts and enable subsequent placement of structural fill or backfill in the dry. Prior to placing submerged fill materials, free water and disturbed materials should be removed to the extent recommended by the geotechnical engineer. A fines barrier geotextile, such as Mirafi 140N or equivalent, should be placed at the base and sides of the overexcavation to separate the crushed stone from underlying and adjacent soils.

The fabric also should be placed on top of the crushed stone prior to subsequent fill placement, if fill soils with a substantial amount of fines are to be used to restore grade.

Compaction and Placement Requirements: Fill and backfill should be placed in loose lifts no more than 12 inches thick when compacted with a vibratory roller compactor weighing at least one ton, and

Hercules Drive

Manchester, Connecticut eight inches when compacted with a plate compactor. Fill and backfill should be compacted to 95 percent of the maximum dry density within three percent of the optimum moisture content, as determined by

ASTM D1557 (Modified Proctor).

Structural Fill Testing: A sample of imported fill material or on-site material proposed for reuse as structural fill or backfill should be submitted to the owner’s geotechnical engineer for analysis and approval at least one week prior to its use. The placement of fill and backfill should be monitored by a qualified engineering technician, so that the specified material and lift thicknesses are properly installed.

A sufficient number of in-place density tests should be conducted, so that the specified compaction is achieved throughout the height of the fill or backfill.

4.3 Groundwater Control

Static groundwater was not encountered during the investigation. However, perched/trapped water may be encountered during construction above non-permeable strata, such as at the bedrock surface. As such, construction phase dewatering may consist of removing surface water runoff, infiltrating water, or trapped water at this site. Whitestone anticipates that construction phase dewatering, if required, would include installing temporary sump pits and filtered pumps within the excavation.

4.4 Foundation Design Criteria

Shallow Foundation: Whitestone recommends supporting the proposed tower on shallow foundations designed to bear within the approved glacial till and/or on controlled structural fill materials that are properly placed and compacted as described herein, or to bear on a layer of crushed stone placed over the bedrock. Where the foundation subgrade is bedrock, the footing should be underlain by a minimum eight-inch thick layer of minus 0.375-inch crushed stone. Foundations bearing within these materials may be designed using a maximum net allowable bearing pressure of 5,000 pounds per square foot. The pad should be placed at least 3.5 feet below adjacent exterior grades, as specified by the Connecticut State Building Code, to provide protection from frost penetration.

A foundation subject to lateral loads and/or overturning should be designed such that the maximum toe pressure due to the combined effect of vertical loads and overturning moment does not exceed the recommended maximum allowable net bearing pressure. In addition, positive contact pressure should be maintained throughout the base of the footing such that no uplift or tension exists between the base of the footing and the supporting soil. Uplift loads should be resisted by the weight of the concrete. Side friction should be neglected when proportioning the footing, such that lateral resistance is provided by friction resistance at the base of the footing. An allowable coefficient of friction against sliding of 0.4 is recommended for use in the design of the foundation bearing within the existing site soils or imported structural fill soils.

Seismic Site Class: The subsurface conditions are most consistent with a Site Class B, as defined by the

Connecticut State Building Code. The site soils are not susceptible to earthquake induced liquefaction.

Inspection/Overexcavation Criteria: Whitestone recommends that the suitability of the bearing materials at the footing bottom be reviewed by a geotechnical engineer immediately prior to placing concrete for the footing. In the event that areas of unsuitable materials are encountered, additional overexcavation and replacement of the materials may be necessary to provide a suitable footing subgrade.

Any overexcavation to be restored with structural fill will need to extend at least one foot laterally beyond footing edges for each vertical foot of overexcavation. Lateral overexcavation may be eliminated if grades are restored with lean concrete.

Hercules Drive

Manchester, Connecticut

Settlement: Whitestone estimates post construction settlement of the shallow foundation would be on the order of less than one inch, with differential settlement of one-half inch, if the recommendations outlined in this report are properly implemented.

4.5 Ancillary Structure Foundations

A lightly loaded ancillary structure housing electrical equipment will be installed close to the base of the tower. Following surficial compaction and proofrolling to densify any upper loose zones, Whitestone anticipates that the properly inspected and approved glacial till and/or controlled structural fill will be suitable for support of a mat foundation for this structure.

The properly prepared on-site soils are expected to yield a minimum subgrade modulus (k) of 150 psi/in.

A nominal net allowable bearing pressure of 2,000 psf is appropriate for the mat, though this is unlikely to govern design. The net allowable bearing pressure may be increased by one third for transient loading conditions. A coefficient of friction (ultimate) against sliding of 0.4 is recommended for use in the design of concrete bearing within the site soils or imported structural fill. Whitestone estimates post-construction settlements will be on the order of less than one inch, if the recommendations outlined in this report are properly implemented. Differential settlements should be less than about one half inch.

A minimum 12-inch layer of CTDOT M.05.01 Processed Aggregate Base (or approved equivalent) should be placed below the mat to provide a uniform subbase. If the mat supports moisture-sensitive equipment, a moisture vapor barrier should be installed beneath the mat in accordance with equipment manufacturer’s recommendations.

The site soils supporting the mat should be properly evaluated by the owner’s geotechnical engineer, and compacted and proofrolled in accordance with the recommendations of this report. Areas of overexcavation should be anticipated if the subgrades are exposed to precipitation. Any areas that become softened or disturbed as a result of wetting and/or repeated exposure to construction traffic should be removed and replaced with compacted structural fill.

A mat constructed as described above would be expected to experience a small amount of heave due to frost action, if water is trapped below the concrete. To reduce the likelihood of heave, either the edges of the mat could be turned down and extended below frost depth of 42 inches or the mat could be supported on shallow frost wall foundations.

4.6 Excavations

The site soils encountered during the investigation generally are most consistent with, at least, Type C Soil Conditions as defined by 29 CFR Part 1926 (OSHA) that require a maximum unbraced excavation angle of 1.5:1 (horizontal:vertical). Actual conditions encountered during construction should be evaluated by a competent person (as defined by OSHA), so that safe excavation methods and/or shoring and bracing requirements are implemented. Competent bedrock may be excavated at an angle of 1:6 (horizontal:vertical). A steeper temporary excavation angle in the bedrock may be feasible, if the exposed bedrock is reviewed by a professional engineer or geologist.

Hercules Drive

Manchester, Connecticut

5.0 SUPPLEMENTAL POST INVESTIGATION SERVICES

Construction Inspection and Monitoring: The owner’s geotechnical engineer with specific knowledge of the site subsurface conditions and design intent should conduct inspection, testing, and consultation during construction as described in previous sections of this report. Monitoring and testing should be conducted to confirm that the existing surface cover materials are properly removed, any encountered underground structures are properly backfilled, and suitable materials, used for controlled fill, are properly placed and compacted over suitable subgrade soils. The proofrolling of all subgrades prior to foundation support should be witnessed and documented by the owner’s geotechnical engineer.

6.0 CLOSING

Whitestone’s Geotechnical Division appreciates the opportunity to be of continued service to New

England Boring Contractors. Please contact us at (860) 726-7889 with any questions regarding this report.

Sincerely, WHITESTONE ASSOCIATES, INC.

Richard W.M. McLaren, P.E. Ryan R. Roy, P.E.

Senior Consultant Vice President

RWM/th N:\Job Folders\2024\2421632GM\Reports and Submittals\NEBC Tower GM2421632 LimGI Manchester CT 4-10-24.doc

Enclosures

Copy: Laurence W. Keller, P.E., Whitestone Associates, Inc.

FIGURE 1

Boring Location Plan

B-1

B-2

B-3

TOWER

CENTER

FIGURE:DATE:

PROJECT #:

SCALE:

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THIS PLAN IS BASED ON A 3/21/22 GOOGLE EARTH IMAGE.

1" = 20'

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NOTE: ALL LOCATIONS ARE APPROXIMATE.

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AutoCAD SHX Text 1 inch = ft.

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AutoCAD SHX Text

APPENDIX A

Records of Subsurface Exploration

1 1

Project:

Location:

Surface Elevation: ± | |

Termination Depth: Date Completed: | |

Proposed Location: | --

At Completion: | -- -- |

| -- 24 Hours: -- |

No Type

0.0

5 - 5.1 S-3 0 - 5.0

10.0

15.0

Rec. RQD

20.0

25.0

BEDROCK

0 - 2 S-1 1 - 6 - 7 - 3 10 13

Boring Log B-1 Terminated at Depth of 15.0 Feet Below Ground Surface.

Proposed Self-Supporting Communications Tower WAI Project No.: GM2421632.000

RECORD OF Boring No.: B-1

SUBSURFACE EXPLORATION Page of

Elevation

15.0 feet bgs 3/21/2024 (feet bgs) (ft NAVD88) (feet bgs) (ft NAVD88)

Hercules Drive, Manchester, Hartford County, Connecticut Client: New England Boring Contractors

NS feet Above NAVD88 Date Started: 3/21/2024 Water Depth Elevation Cave-In Depth

--Drill / Test Method: HSA / SPT Contractor: MS --

Tower Logged By: MM During: --

At Completion:

SAMPLE INFORMATION DEPTH

STRATA DESCRIPTION OF MATERIALS REMARKS

Depth

(feet) Blows Per 6"

Rec.

(in.) N (feet) (Classification)

NQ2 Core Equipment: Mobile B-53 24 Hours:

TS 6" Topsoil

No Recovery

TILL

Brown, Medium Dense, Silty Sand with Gravel (SM)

GLACIAL

Cobbles

As Above, Dense (SM)

Time (minutes/ft)

S-2 5 -

50/1"

5 - 10 C-1 NQ2

1.5

36"

60%

RQD

20%

1.5

1.5

1.8

2 - 2.8 9 - 50/3"

Gray, Moderately Weathered, Coarse to Very Coarse Grained, Medium Bedded, Hard, Sandstone and Conglomerate

Gray, Moderately Weathered, Coarse to Very Coarse Grained, Medium Bedded, Hard, Sandstone and Conglomerate

10 - 15 C-2 NQ2

36"

60%

RQD

9%

NOTES: bgs = below ground surface, msl = mean sea level, NA = Not Applicable, NE = Not Encountered, NS = Not Surveyed, P = Perched RECORD OF SUBSURFACE EXPLORATION

NEBC Comm Tower Manchester CT GM2421632 Boring Logs 3-21-24 4/9/2024

Location:

Surface Elevation: ± | |

Termination Depth: Date Completed: | |

Proposed Location: | --

At Completion: | -- -- |

| -- 24 Hours: -- |

No Type

0.0

2.5

5.0

10.0

15.0

20.0

25.0

Proposed Self-Supporting Communications Tower WAI Project No.: GM2421632.000

RECORD OF Boring No.: B-2

SUBSURFACE EXPLORATION Page of

Elevation

6.0 feet bgs 3/21/2024 (feet bgs) (ft NAVD88) (feet bgs) (ft NAVD88)

Hercules Drive, Manchester, Hartford County, Connecticut Client: New England Boring Contractors

NS feet Above NAVD88 Date Started: 3/21/2024 Water Depth Elevation Cave-In Depth

Drill / Test Method: HSA / SPT Contractor: MS -- At Completion: --

Tower Logged By: MM During: --

--Equipment: Mobile B-53 24 Hours: --

0 - 2 S-1 11 -

SAMPLE INFORMATION DEPTH

STRATA DESCRIPTION OF MATERIALS REMARKS

Depth

(feet) Blows Per 6"

Rec.

(in.) N (feet)

7 - 7 - 8 8

(Classification)

BEDROCK

2 -

TS 6" Topsoil

Brown, Medium Dense, Silty Sand with Gravel (SM)

GLACIAL

TILL

Weathered Bedrock

Boring Log B-2 Terminated upon Auger Refusal at Depth of 3.0 fbgs.

As Above (SM) 2 - 2.8 S-2 10 - 50/4"

NOTES: bgs = below ground surface, msl = mean sea level, NA = Not Applicable, NE = Not Encountered, NS = Not Surveyed, P = Perched RECORD OF SUBSURFACE EXPLORATION

Location:

Surface Elevation: ± | |

Termination Depth: Date Completed: | |

Proposed Location: | --

At Completion: | -- -- |

| -- 24 Hours: -- |

No Type

0.0

5.0

5 - 5.4 S-3 2 -

10.0

15.0

20.0

25.0

Proposed Self-Supporting Communications Tower WAI Project No.: GM2421632.000

RECORD OF Boring No.: B-3

SUBSURFACE EXPLORATION Page of

Elevation

6.0 feet bgs 3/21/2024 (feet bgs) (ft NAVD88) (feet bgs) (ft NAVD88)

Hercules Drive, Manchester, Hartford County, Connecticut Client: New England Boring Contractors

NS feet Above NAVD88 Date Started: 3/21/2024 Water Depth Elevation Cave-In Depth

Drill / Test Method: HSA / SPT Contractor: MS -- At Completion: --

Tower Logged By: MM During: --

--Equipment: Mobile B-53 24 Hours: --

SAMPLE INFORMATION DEPTH

STRATA DESCRIPTION OF MATERIALS REMARKS

Depth

(feet) Blows Per 6"

Rec.

(in.) N (feet)

5 11

(Classification)

0 - 2 S-1 2 -

2 - 4 S-2 5 - 15 - 17

TS 4" Topsoil

Brown, Loose to Medium Dense, Silty Sand with Gravel (SM) 5 - 5 -

As Above, Dense (SM)

- 22 19 32

GLACIAL

TILL

50/5"

Boring Log B-3 Terminated upon Auger Refusal at Depth of 6.0 fbgs.

BEDROCK Weathered Bedrock

NOTES: bgs = below ground surface, msl = mean sea level, NA = Not Applicable, NE = Not Encountered, NS = Not Surveyed, P = Perched RECORD OF SUBSURFACE EXPLORATION

APPENDIX B

Supplemental Information

(USCS, Terms & Symbols)

ROCKY HILL, CT 06067

UNIFIED SOIL CLASSIFICATION SYSTEM

SOIL CLASSIFICATION CHART

MAJOR DIVISIONS

LETTER

SYMBOL

TYPICAL DESCRIPTIONS

COARSE

GRAINED

SOILS

MORE THAN

50% OF

MATERIAL IS

LARGER THAN

NO. 200 SIEVE

SIZE

GRAVEL AND

GRAVELLY SOILS

MORE THAN 50% OF

COARSE FRACTION

RETAINED ON NO. 4

SIEVE

CLEAN

GRAVELS

(LITTLE OR

NO FINES)

GW WELL-GRADED GRAVELS, GRAVEL-SAND

MIXTURES, LITTLE OR NO FINES

GP POORLY-GRADED GRAVELS, GRAVEL-

SAND MIXTURES, LITTLE OR NO FINES

GRAVELS WITH

FINES

(APPRECIABLE

AMOUNT OF

FINES)

GM SILTY GRAVELS, GRAVEL-SAND-SILT

MIXTURES

GC CLAYEY GRAVELS, GRAVEL-SAND-CLAY

MIXTURES

SAND AND SANDY

MORE THAN 50% OF

COARSE FRACTION

PASSING NO. 4

SIEVE

CLEAN SAND

(LITTLE OR NO

FINES)

SW WELL-GRADED SANDS, GRAVELLY SANDS,

LITTLE OR NO FINES

SP POORLY-GRADED SANDS, GRAVELLY

SANDS, LITTLE OR NO FINES

SANDS WITH

FINES

(APPRECIABLE

AMOUNT OF

FINES)

SM SILTY SANDS, SAND-SILT MIXTURES

SC CLAYEY SANDS, SAND-CLAY MIXTURES

FINE

GRAINED

MORE THAN

50% OF

MATERIAL IS

SMALLER THAN

NO. 200 SIEVE

SIZE

SILTS

AND

CLAYS

LIQUID LIMITS

LESS THAN 50

ML INORGANIC SILTS AND VERY FINE SANDS,

ROCK FLOUR, SILTY OR CLAYEY FINE

SANDS OR CLAYEY SILTS WITH SLIGHT

PLASTICITY

CL INORGANIC CLAYS OF LOW TO MEDIUM

PLASTICITY, GRAVELLY CLAYS, SANDY

CLAYS, SILTY CLAYS, LEAN CLAYS

OL ORGANIC SILTS AND ORGANIC SILTY

CLAYS OF LOW PLASTICITY

SILTS

AND

CLAYS

LIQUID LIMITS

GREATER

THAN 50

MH INORGANIC SILTS, MICACEOUS OR

DIATOMACEOUS FINE SAND OR SILTY

SOILS

CH INORGANIC CLAYS OF HIGH PLASTICITY,

FAT CLAYS

OH ORGANIC CLAYS OF MEDIUM TO HIGH

PLASTICITY, ORGANIC SILTS

HIGHLY ORGANIC SOILS PT PEAT, HUMUS, SWAMP SOILS WITH HIGH

ORGANIC CONTENTS

NOTE: DUAL SYMBOLS ARE USED TO INDICATE BORDERLINE SOIL CLASSIFICATIONS FOR SAMPLES WITH 5% TO 12% FINES

GRADATION* COMPACTNESS*

Sand and/or Gravel

CONSISTENCY*

Clay and/or Silt

% FINER BY WEIGHT RELATIVE

DENSITY

RANGE OF SHEARING STRENGTH IN

POUNDS PER SQUARE FOOT

TRACE........... 1% TO 10%

LITTLE.......... 10% TO 20%

SOME............ 20% TO 35%

AND............... 35% TO 50%

LOOSE. .................. 0% TO 40%

MEDIUM DENSE.... 40% TO 70%

DENSE................... 70% TO 90%

VERY DENSE........ 90% TO 100%

VERY SOFT....... LESS THAN 250

SOFT.................... ..... 250 TO 500

MEDIUM................... 500 TO 1000

STIFF..................... 1000 TO 2000

VERY STIFF.......... 2000 TO 4000

HARD...... GREATER THAN 4000

* VALUES ARE FROM LABORATORY OR FIELD TEST DATA, WHERE APPLICABLE.

WHEN NO TESTING WAS PERFORMED, VALUES ARE ESTIMATED.

L:\Geotechnical Forms and References\Reports\USCSTRMSSYM CT.docx

ROCKY HILL, CT 06067

GEOTECHNICAL TERMS AND SYMBOLS

SAMPLE IDENTIFICATION

The Unified Soil Classification System is used to identify the soil unless otherwise noted.

SOIL PROPERTY SYMBOLS

N: Standard Penetration Value: Blows per ft. of a 140 lb. hammer falling 30" on a 2" O.D. split-spoon.

Qu: Unconfined compressive strength, TSF.

Qp: Penetrometer value, unconfined compressive strength, TSF.

Mc: Moisture content, %.

LL: Liquid limit, %.

PI: Plasticity index, %.

δd: Natural dry density, PCF.

▾: Apparent groundwater level at time noted after completion of boring.

DRILLING AND SAMPLING SYMBOLS

NE: Not Encountered (Groundwater was not encountered).

SS: Split-Spoon - 1 ⅜” I.D., 2" O.D., except where noted.

ST: Shelby Tube - 3” O.D., except where noted.

AU: Auger Sample.

OB: Diamond Bit.

CB: Carbide Bit

WS: Washed Sample.

RELATIVE DENSITY AND CONSISTENCY CLASSIFICATION

Term (Non-Cohesive Soils) Standard Penetration Resistance

Very Loose 0-4

Loose 4-10

Medium Dense 10-30

Dense 30-50

Very Dense Over 50

Term (Cohesive Soils) Qu (TSF)

Very Soft 0 - 0.25

Soft 0.25 - 0.50

Firm (Medium) 0.50 - 1.00

Stiff 1.00 - 2.00

Very Stiff 2.00 - 4.00

Hard 4.00+

PARTICLE SIZE

Boulders 8 in.+ Coarse Sand 5mm-0.6mm Silt 0.074mm-0.005mm

Cobbles 8 in.-3 in. Medium Sand 0.6mm-0.2mm Clay -0.005mm

Gravel 3 in.-5mm Fine Sand 0.2mm-0.074mm

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