Attachment 26 - 4276-001 Geotechnical Report.pdf

GEODesign, Inc.

984 Southford Rd.

Middlebury, CT 06762

(203) 758-8836

January 31, 2023

File No. 4276-001.00

Amador Laput, Project Manager

Fellenzer Engineering, LLP

22 Mulberry Street, Suite 2A

Middletown, NY 10940

Via Email: acl@fellp.com

Re: Geotechnical Engineering Report

West Haven VA Medical Center Sterile Processing Service Wing (SPSW)

950 Campbell Avenue

West Haven, Connecticut

Dear Amador:

GEODesign, Inc. (GEODesign) is pleased to submit our geotechnical engineering report for the proposed new SPSW for the West Haven VA Medical Center located at 950 Campbell Avenue in

West Haven, Connecticut. The general site location is depicted on Figure 1 in Appendix 1. The building layout and site plan is shown on Figure 2 in Appendix 1.

PURPOSE AND SCOPE

GEODesign completed a subsurface exploration program and geotechnical engineering report for the proposed new Building 31, which will serve as the new SPSW, and associated improvements.

Our services included exploring the subsurface conditions with borings in the project area, performing geotechnical engineering analyses, laboratory testing, and providing geotechnical design recommendations. Our services were provided in accordance with our most recently revised proposal originally dated November 8, 2022 and revised on January 16, 2023.

Our recommendations are based in part on guidance from the 2015 International Building Code

(IBC) and the 2022 Connecticut State Building Code.

BACKGROUND

The site is located along the western (southbound) side of Campbell Avenue and the proposed new

SPSW building will be located near the southeastern corner of the West Haven VA Medical Center property. Existing site conditions and selected details regarding the proposed development are shown on the Boring Location Plan, included as Figure 2 in Appendix 1. The site is currently occupied by the existing VA Medical Center buildings/facilities and associated driveways and parking areas.

mailto:acl@fellp.com

West Haven Medical Center SPSW

West Haven, Connecticut

File No. 4276-001.00 – January 31, 2023

Page No. 2

Our understanding of the project site is based on multiple site meetings, a review of the drawings provided to us by Fellenzer Engineering, LLP (Fellenzer), and our correspondence with Fellenzer.

The plans depict existing grades, locations of mapped underground utilities, a conceptual layout of the proposed improvements, and selected existing conditions. Based on our correspondence with Fellenzer, we understand that the existing Building 31 will be demolished and the new SPSW building will be located in approximately the same location but will extend further north and west than the existing structure.

We understand that the proposed SPSW building will be approximately 7,000 square feet

(approximately 70 feet by 100 feet) and will have one floor below ground and one floor above ground.

Information regarding anticipated structural loads was not available at the time this report was prepared. For the purpose of this report, we are assuming that the lower-level slab will be approximately 8 below existing ground (El. 87)

SUBSURFACE EXPLORATIONS

GEODesign performed, observed, and logged two test borings (referenced as Borings B-1 and B-

2) drilled by General Borings, Inc. on January 17, 2023 using an ATV-mounted drill rig. The boring locations are depicted on Figure 2 in Appendix 1, and boring logs are included in Appendix

2.

GEODesign engineering staff attended multiple site meetings with Fellenzer and West Haven VA

Medical Center personnel to plan out the proposed boring locations. Due to a relatively high quantity of underground utilities located within the proposed building footprint, GEODesign retained Underground Surveying, LLC, a ground penetrating radar (GPR) subcontractor, to assist in locating any mapped and unmapped underground utilities on site within the general vicinity of the proposed boring locations. The GPR subcontractor only marked any utilities that they encountered within the limitations of their equipment. The report from the GPR subcontractor is included in Appendix 3. The foregoing conditions limited the ability to complete more than two borings.

The as-drilled boring locations were determined by taping from existing site features. We interpolated the ground surface elevations at the boring locations from the topographic contour lines shown on the above-referenced plans. The locations of the borings and their elevations are approximate.

The explorations were advanced using hollow-stem augers to depths of approximately 10.8 to 20.5 feet below existing site grades. Representative soil samples were obtained by split barrel sampling procedures in general accordance with ASTM Specification D-1586. The split-barrel sampling procedure utilizes a standard 2-inch O.D. split-barrel sampler that is driven into the bottom of the boring with a 140-pound hammer falling a distance of 30 inches. The number of blows required to

West Haven, Connecticut

Page No. 3 advance the sampler the middle 12 inches of a 24-inch penetration is recorded as the Standard

Penetration Resistance Value (N), presented in blows per foot (bpf). The blows (i.e., the "N" values) are indicated on the boring logs at their depth of occurrence and provide an indication of the relative consistency of the material.

In Boring B-2, concrete was encountered at a depth of approximately 10.7 feet beneath existing site grades (approximately El. 84.3). The undersigned discussed this with Mr. Amador Laput

(Project Manager, Fellenzer) and Peter Sandor (Healthcare Engineer, West Haven VA Medical

Ccenter), and Mr. Laput advised GEODesign personnel to terminate this boring rather than attempting to drill through the concrete.

Rock coring was performed using a 5-foot long NX core barrel to verify the presence of rock and to assess its quality, as indicated by core recovery and rock quality designation (RQD). RQD is defined as the combined length of pieces of the core sample greater than 4 inches in length divided by the total core length. A five foot long rock core sample was collected from Boring B-1 at a depth of approximately 20.5 feet beneath existing grades. The use of a geophysical survey to determine a detailed bedrock profile was not chosen by Fellenzer.

Groundwater was not encountered in the borings within the depths explored (up to a maximum depth of approximately 25.5 feet below existing site grades).

We performed two borings east of this site for another project. Those borings were approximately

100 feet east of the proposed structure. These borings encountered fill to depths of approximately

5 to 13 beneath existing site grades, before encountering bedrock directly below the fill.

LABORATORY TESTING

Representative soil samples were sent to TerraSense, LLC of Totowa, New Jersey for sieve analysis to verify the field classifications and assist in engineering evaluations. Laboratory test results are pending and will be forwarded separately.

SUBSURFACE CONDITIONS

Geology

In conjunction with our subsurface exploration, we reviewed published geological data of the site vicinity (the “Geologic Map of the New Haven and Woodmont Quadrangles, Connecticut,”

Richard Foster Flint, 1965, (map scale: 1:24,000) and the “Bedrock Geological Map of

Connecticut,” John Rodgers, 1985, (map scale: 1:125,000)).

The available geologic information indicates that the surficial materials are mapped as till, which is described as a poorly sorted, generally nonstratified heterogenous mixture of soil and rock

West Haven, Connecticut

Page No. 4 particles ranging in size from boulders to clay. The underlying bedrock is mapped as Oronoque

Schist, which is described as gray to silver, medium- to fine-grained schist and granofels.

General Subsurface Profile

The subsurface conditions were generally consistent with the mapped surficial geology. The generalized subsurface profile, as inferred from the subsurface explorations, consists of surficial materials (i.e., topsoil or asphalt), fill, glacial till, and bedrock. A brief description of the subsurface conditions encountered by the explorations is presented in the following paragraphs.

Surficial Materials were encountered at the ground surface in both borings. An approximately 3-inch-thick layer of Asphalt was encountered in Boring B-1 and an approximately 3-inch-thick layer of Topsoil was encountered in Boring B-2.

Fill was encountered immediately below the Surficial Materials in both borings. The fill extended to a depth of approximately 13.5 feet beneath existing grades and was visually classified as gray to brown, fine to coarse sand, trace (1-10%) to primary (>50%) amounts of fine to coarse gravel, trace to some (20-35%) silt, trace-minus (1-3%) brick fragments, and trace-minus organic fibers.

Based on an SPT N-values of 4 bpf to 24 bpf, the fill was inferred to be loose to medium dense.

Glacial Till was encountered beneath the Fill in Boring B-1 and extended to depths of approximately 20.5 feet beneath existing grades. The Glacial Till was visually classified as red-brown, fine to coarse sand, some silt, and little (10-20%) fine gravel. Based on SPT N-values of

34 and 50 blows for 2 inches of penetration, the glacial till was inferred to be dense to very dense.

Bedrock was encountered beneath the Glacial Till in Boring B-1, at a depth of approximately 20.5 feet beneath existing grades. Based on an RQD of 15.8 percent, the bedrock is inferred to be of very poor quality. The bedrock was visually classified as moderately hard, moderately weathered, gray schist.

Groundwater was not encountered during the drilling within approximately 20.5 feet of existing grades. Note that groundwater depths will vary in response to seasonal variations in precipitation and may be impacted by construction activity or other factors.

GEOTECHNICAL RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

Building Foundation and Slabs

The results of the borings and observations made during site visits indicate fills are present to depths of as much as approximately 13.5 feet in the borings or approximately 15 feet based on observations while opening the existing manholes on site (invert of the pipe in the manhole was approximately 15 feet below existing site grades). Existing fill is not suitable for direct foundation

West Haven, Connecticut

Page No. 5 or slab support. If encountered at slab/footing subgrades, these materials should be completely removed.

Conditions are favorable for shallow spread footings bearing on undisturbed natural glacial till, compacted Structural Fill, or improved Fill (i.e., densified in place) for support of the building.

Overexcavated areas should be backfilled with compacted Structural Fill. Where footings are placed on Structural Fill, the fill should extend outward beyond the building limits on a one-to-one downward slope from 1 foot outside of the exterior edge of footing. This will form a truncated pyramid of structural fill support below the footings.

Provided the recommendations presented above are implemented, footings may be proportioned for a net allowable bearing pressure of 4,000 pounds per square foot (psf), subject to our review when information regarding structural loads becomes available. We recommend minimum footings sizes of 36 inches for column footings and 24 inches for strip footings. We anticipate that footings designed for the above bearing pressure will experience less than 1 inch total and ½ differential settlement. Settlement is expected to occur during construction.

Exterior footings and footings in areas otherwise subjected to freezing temperatures must be embedded at least 3½ feet below grade consistent with building code frost protection requirements.

Interior footings in heated areas shall bear no less than 18 inches below the top of the finished slab.

We assume that the concrete slabs will be constructed as conventional slabs on grade. The slabs should be constructed on minimum 6-inch layers of freshly placed imported Gravel Fill or Crushed

Stone bearing on the firm natural soils or compacted Structural Fill. The Gravel Fill/Crushed Stone should be compacted with a vibratory plate or roller compactor and recompacted immediately before final preparations for concrete placement.

A subgrade modulus of 200 pounds per cubic inch (pci) may be assumed for slab design.

Base Friction Factor

Per Table 1806.2 of the 2022 Connecticut State Building Code, we recommend a coefficient of friction of 0.35 for footings bearing on Structural Fill.

Earthquake Design

We anticipate that Site Class “D” (stiff soil) can be utilized for the design in accordance with the procedures outlined in ASCE 7-16, Chapter 20. Per Appendix N of the 2022 Connecticut State

Building Code, Ss equals 0.200 and S1 equals 0.053 for West Haven.

We do not consider site soils subject to liquefaction.

West Haven, Connecticut

Page No. 6

Design for Lateral Load

Basement walls, site retaining walls (if planned), or other structures subjected to unbalanced lateral earth pressures should be designed using the following parameters:

Parameter Value1

Equivalent Fluid Pressure (Active Case) 35 pcf

Equivalent Fluid Pressure (At-Rest Case) 55 pcf

Unit Weight γ 125 pcf

Friction Angle Φ 34°

Active Earth Pressure Coefficient Ka 0.28

At-Rest Earth Pressure Coefficient K0 0.44 1Abbreviation: pounds per cubic foot (pcf).

The above recommendations are presented based on the assumption that the proposed walls will not be subjected to hydrostatic pressures. To achieve this condition, free-draining backfill must be used for wall backfill. Standard gravity foundation drains are also recommended.

Walls subject to surcharge loads must also be designed for an additional uniform lateral pressure over the entire height of the wall equal to the applicable earth pressure coefficient (active or at-rest case, as applicable) times the magnitude of the surcharge.

Excavation

The on-site fill and natural soils are considered to be Type “C” soils per the Occupational Safety and Health Administration (OSHA) standards. As such, temporary excavations should be sloped at 1.5H:1V when seepage is not present.

Boring B-1 encountered bedrock at a depth of approximately 20.5 feet beneath existing grades, roughly corresponding to El. 75.5. The remaining borings did not encounter bedrock above the anticipated foundation/slab subgrade elevations. However, given the generally shallow depth to bedrock at the site, rock removal may be required in some areas.

We anticipate that diversion trenches and pumps will be adequate to control any groundwater, if encountered, during construction. Excavations should be also protected from precipitation and run-off of surface drainage.

Foundation and Slab Drainage

We recommend a perimeter footing drain that daylights and flows by gravity to the site drainage system. A sump pump may also be advisable to keep the slab subgrade drained.

West Haven, Connecticut

Page No. 7

As a minimum, slab damp-proofing should be installed between the slab and base course and consist of not less than 6-mil polyethylene with joints lapped at least 6 inches and sealed in accordance with the manufacturer’s recommendations. Additional waterproofing measures may be considered depending on the level of moisture/flood protection desired.

Fill and Backfill

Structural Fill to be used below pavement, as backfill in overexcavated areas, and other applications as detailed shall be environmentally clean and free of ash, refuse, trash, ice, snow, stumps, roots, organic materials and other deleterious materials. The environmental engineer should review any special requirements or restrictions for below slab fill.

Structural Fill shall not include asphalt or bituminous rubble except in locations directly below proposed exterior paved areas. Significant quantities of Structural Fill are not expected to be obtained from on-site sources.

Structural Fill obtained from off-site sources shall be well graded within the following limits:

Sieve Size Percent Passing by Weight

6” No. 10 No. 40 No. 200

30-95 10-70 0-15

Select Fill for use as backfill behind drained walls and other applications requiring free draining, non–frost susceptible backfill shall be free of ice, snow, roots, sod, rubbish and other deleterious or organic matter and shall conform to the following gradation requirements:

Sieve Size Percent Passing by Weight

6” No. 10 No. 40 No. 200

30-95 10-70 0-10

Ordinary Fill for use as fill or backfill where other materials are not specified shall be friable, nonplastic, inorganic soil containing no stone greater than 2/3 of the required loose lift thickness and not more than 35 percent passing the No. 200 sieve. Ordinary Fill shall be free of ash, refuse, trash, ice, snow, stumps, roots, and organic materials.

Gravel Fill shall meet the requirement of ConnDOT Form 817, article M.02.01, Grading A or C.

Crushed Stone shall meet the requirements of ConnDOT Form 817, article M.0.01 for sizes No. 6, No. 67 or No. 8.

Processed Aggregate Base shall meet the requirements of ConnDOT Form 817, article M.05.01.

West Haven, Connecticut

Page No. 8

Materials should be placed within 3 percent of their optimum moisture content and compacted in accordance with the following table.

Compaction

Method

Maximum

Stone

Size*

Maximum Loose Lift

Thickness

Minimum Number of

Passes

Below

Structures and

Pavement

Less

Critical

Area

Below

Structures and

Pavement

Less

Critical

Area

Hand-operated vibratory plate or light roller in confined areas

4" 6" 8" 6 4

Hand-operated vibratory drum rollers weighing at least 1,000# in confined areas

6" 8" 10" 6 4

Light vibratory drum roller minimum dynamic force

3,000#/ft. drum width

6"

10"

12"

Medium vibratory drum roller

5,000#/ft. drum width

8"

12"

16"

Heavy vibratory drum roller

8,000#/ft. drum width

10"

16"

18"

* And no more than two-thirds (2/3) loose lift thickness.

We recommend a minimum in-place dry density of 95-percent as per ASTM D1557 for material placed below foundations and slabs. We recommend a minimum in-place dry density of 92-percent as per ASTM D1557 for material placed below paved areas and as backfill exterior to foundations.

CONSTRUCTION DOCUMENTS AND SPECIAL INSPECTIONS

GEODesign remains available to collaborate with the design team to finalize design details and address geotechnical related issues that arise during design development. GEODesign’s involvement is recommended in regard to preparation of project technical specifications for earthwork, and review of construction drawings and related technical specification sections prepared by other design team members.

We do not recommend that the geotechnical engineering report be included in the bid documents since it contains interpretive information and may include concepts or recommendations that were not incorporated into the final project design. Instead, certain factual subsurface exploration data

(boring logs and the like) should be extracted from the geotechnical engineering report and included in the bidder’s information. The geotechnical report text itself is best not included in the bid documents, but should be referenced and made available for the bidder’s information only.

West Haven, Connecticut

Page No. 9

Consistent with building code requirements, placement of structural fill supporting building foundations and preparation of footing subgrades are subject to “special inspection” requirements.

The geotechnical Special Inspector must review excavated subgrades for foundations and slabs and determine any requirements to additional excavation and replacement of unsuitable material.

Our recommendations are predicated on our involvement to allow evaluation of actual conditions exposed during construction to address variations versus anticipated conditions and to allow prompt response for any necessary modifications.

This report and GEODesign’s services are subject to the limitations outlined in Appendix 4.

Dylan Carlson, P.E. Theodore von Rosenvinge, P.E.

Senior Staff Engineer Senior Principal m:\cl\4276 fellenzer\001\04 report\4276-001 report final.docx

Attachments:

Appendix 1 – Figures

Appendix 2 – Boring Logs

Appendix 3 – GPR Report

Appendix 4 – Limitations

Appendix 1

Figures

984 SOUTHFORD ROAD

MIDDLEBURY, CT 06762

203.758.8836 geocompanies.com

984 SOUTHFORD ROAD

MIDDLEBURY, CT 06762

203.758.8836 geocompanies.com

Appendix 2

Boring Logs

1) Existing ground surface elevation was interpolated from topographic data from the plan titled "Civil: Temporary Egress Plan" by Fellenzer Engineering, LLP. Original date: October 21, 2022.

2) Piece of gravel stuck in shoe of spoon on Sample S-5.

3) Increased drilling effort required at depths of approximately 17'-20.5'.

4) Auger refusal at a depth of approximately 20.5'.

13.5

20.5

25.5

13.5

20.5

25.5

Top 3": ASPHALT Bottom 5": Medium dense, gray to brown, fine to coarse SAND, some fine to coarse Gravel, little Silt

Medium dense, gray to black, fine to coarse GRAVEL, some fine to coarse Sand, trace Silt

Loose, gray to brown, fine to coarse GRAVEL, some fine to coarse Sand, little Silt

Loose, gray to brown, fine to coarse SAND, some fine to coarse Gravel, some Silt

Loose, brown, fine to coarse SAND, some Silt, some (-) fine to coarse Gravel

Dense, red-brown, fine to coarse SAND, some Silt, little fine Gravel

Very dense, gray, fine GRAVEL, some fine to coarse Sand, trace Silt Very poor quality, gray, moderately hard, moderately weathered SCHIST

RQD=9.5"/60"=15.8%

95.7

82.5

75.5

70.5

ASPHALT

FILL

GLACIAL

TILL

BEDROCK

Bottom of Exploration at 25.5 ft

B O

R

IN

G L

O G

M C

J

A N

U A

R Y

B O

R

IN

G

LO

G S

.G P

J G

E O

D E

S

IG

N S

T A

N D

A R

D .G

D T

1/

/2

Groundwater Observations

D ep th ft

Casing:

Notes:

E. Coordinate:

Date

T yp e

0 - 6

Ground Surface Elevation (feet):

Sampler:

Rig Type:

Depth & Elevation(feet)

Boring Company:

C as in g

B lo w s/ ft West Haven VA Hospital SPS Wing

950 Campbell Ave West Haven, CT

Project Name

Date Started:

R ec ov er y (i nc he s)

None encountered

Pe ne tr at io n

(i nc he s)

1) Stratification lines represent approximate boundary between material types, transitions may be gradual.

2) Water level readings have been made at times and under conditions stated, fluctuations of groundwater may occur due to other factors than those present at the time measurements were made. AC = After coring; NR = Not Recorded.

3) Abbreviations: A = Auger; C = Core; MC=Macrocore; D = Driven; G = Grab; PS = Piston Sample; SS = Split Spoon; SSL = 3.5 Inch ID Split Spoon; ST = Shelby Tube;

V = Vane; WOR/H = Weight of Rod/Hammer

4) Proportions Used: Trace = 1-10%; Little = 10-20%; Some = 20-35%; And = 35-50%

984 Southford Road - Middlebury, CT 06762 Telephone: 203-758-8836 Fax:

Foreman:

Sy m bo l

Classification System: Modified Burmister6 - 12

Elev.

(ft)

R em ar ks

Hammer Type:

Boring No.:

Geotechnical | Construction | Environmental Engineers and Scientists

Dylan Carlson

Jim Casson

N/A

Automatic - Hydraulic

Diedrich D50 Track

H.S.A.

January 17, 2023

General Borings, Inc.

Boring No.:

Page No.:

File No.:

Checked By:

30 in.N/A

Blows / 6 inch Interval

12 - 18

Notes

GeoDesign Rep.:

Hammer Wt.:

Depth (ft)

N. Coordinate:

D ep th ft

SS

140 lbs

1.38 in.

N um be r

Hammer Fall:

January 17, 2023 1/17/23

Sample Description

18 - 24

Strata Description

3.25 in.

Sample Information

Station:

C or in g

T im e (m in ./f t)

Date Finished:

BORING LOG

B-1

B-1 ft

M oi st ur e C on te nt

Jim Casson

Offset:

4276-001

TLC

Type:

I.D.:

[REC= 100%; RQD= 9.5%]

50/2"

50/2"

0.0

2.0

5.0

7.0

10.0

15.0

20.0 20.5

SS

SS

SS

SS

SS

SS

SS

C

0.5

1) Existing ground surface elevation was interpolated from topographic data from the plan titled "Civil: Temporary Egress Plan" by Fellenzer Engineering, LLP. Original date: October 21, 2022.

2) Encountered concrete at the bottom of Sample S-5 (spoon refusal and concrete in tip of spoon). Terminated boring per discussion with Amador Laput (Project Manager, Fellenzer) and Peter Sandor (Healthcare Engineer, West Haven VA Hospital).

10.710.7

Top 3": Dark brown, TOPSOIL Bottom 2": Medium dense, brown, fine to coarse SAND, trace fine Gravel, trace Silt, trace (-) Brick Fragments, trace (-) Organic Fibers

Medium dense, brown, fine to coarse SAND, some fine to coarse Gravel, little Silt, trace (-) Brick Fragments, trace (-) Organic Fibers Medium dense, gray to brown, fine to coarse SAND, little fine to coarse Gravel, trace Silt

Loose, gray to brown, fine to coarse SAND, some fine Gravel, little Silt

Very dense, no recovery (concrete in tip of spoon)

94.7

84.3 84.2

TOPSOIL

FILL

CONCRETE

Bottom of Exploration at 10.8 ft

B O

R

IN

G L

O G

M C

J

A N

U A

R Y

B O

R

IN

G

LO

G S

.G P

J G

E O

D E

S

IG

N S

T A

N D

A R

D .G

D T

1/

/2

Groundwater Observations

D ep th ft

Casing:

Notes:

E. Coordinate:

Date

T yp e

0 - 6

Ground Surface Elevation (feet):

Sampler:

Rig Type:

Depth & Elevation(feet)

Boring Company:

C as in g

B lo w s/ ft West Haven VA Hospital SPS Wing

950 Campbell Ave West Haven, CT

Project Name

Date Started:

R ec ov er y (i nc he s)

None encountered

Pe ne tr at io n

(i nc he s)

1) Stratification lines represent approximate boundary between material types, transitions may be gradual.

2) Water level readings have been made at times and under conditions stated, fluctuations of groundwater may occur due to other factors than those present at the time measurements were made. AC = After coring; NR = Not Recorded.

3) Abbreviations: A = Auger; C = Core; MC=Macrocore; D = Driven; G = Grab; PS = Piston Sample; SS = Split Spoon; SSL = 3.5 Inch ID Split Spoon; ST = Shelby Tube;

V = Vane; WOR/H = Weight of Rod/Hammer

4) Proportions Used: Trace = 1-10%; Little = 10-20%; Some = 20-35%; And = 35-50%

984 Southford Road - Middlebury, CT 06762 Telephone: 203-758-8836 Fax:

Foreman:

Sy m bo l

Classification System: Modified Burmister6 - 12

Elev.

(ft)

R em ar ks

Hammer Type:

Boring No.:

Geotechnical | Construction | Environmental Engineers and Scientists

Dylan Carlson

Jim Casson

N/A

Automatic - Hydraulic

Diedrich D50 Track

H.S.A.

January 17, 2023

General Borings, Inc.

Boring No.:

Page No.:

File No.:

Checked By:

30 in.N/A

Blows / 6 inch Interval

12 - 18

Notes

GeoDesign Rep.:

Hammer Wt.:

Depth (ft)

N. Coordinate:

D ep th ft

SS

140 lbs

1.38 in.

N um be r

Hammer Fall:

January 17, 2023 1/17/23

Sample Description

18 - 24

Strata Description

3.25 in.

Sample Information

Station:

C or in g

T im e (m in ./f t)

Date Finished:

BORING LOG

B-2

B-2 ft

M oi st ur e C on te nt

Jim Casson

Offset:

4276-001

TLC

Type:

I.D.:

0.0

2.0

5.0

7.0

10.0

50/4"

SS

SS

SS

SS

SS

Appendix 3

GPR Report

Utility Locating Survey Report

West Haven VA Hospital 950 Campbell Ave.

West Haven, CT

Prepared for Dylan Carlson of GeoDesign, Inc.

Introduction

A utility locating survey was performed by Underground Surveying, LLC of 72 Gray’s Bridge Road, Unit Q, Brookfield, CT for GeoDesign, Inc. of 984 Southford Road, Middlebury, CT, on December 8, 2022 at 950 Campbell Ave., West Haven, CT. The purpose of the survey was to mark the location of underground utilities running within the area housing the 4 proposed boring locations marked in red on the boring plan shown below.

Technology

The survey was performed with cable and pipe locator and ground-penetrating radar (GPR) technology. If you are not familiar with how this technology works and what its limitations are, we recommend that you read the following information shown below.

Cable & Pipe Locator

We currently use RD8000 cable and pipe locators for all our utility locating needs. This model of equipment, which is manufactured by the Radiodetection Corp., is widely recognized as the industry standard because it maintains the highest locate performance, contains multiple locate modes, and is fairly easy to use.

The science behind cable and pipe locating is based on the principle that a current flowing along a conductor creates a magnetic field, and that this magnetic field or signal, which is either passive or active in nature, can be detected via a receiver.

A passive signal is one that is naturally occurring around a conductor, or in this case an underground utility. Some examples of passive signals include the following:

1. Current flowing in an electric supply cable.

2. Earth return current from power systems that use metal pipes or cable sheaths as a convenient conductor.

3. Radio frequency currents from very low frequency (VLF) radio transmissions that have penetrated the ground and flow along a buried utility.

The most basic technique of cable and pipe locating is a passive sweep. This technique is used to search for inaccessible, abandoned, or unknown utilities using a receiver without the use of a transmitter. To perform a passive sweep, a survey grid is traversed in “power” mode with the receiver blade in line with the direction of movement and at right angles to the suspected path of underground utilities. When the receiver indicates the presence of a utility, it is pinpointed, traced, and marked. The sweep is continued until all detected utilities have been marked and the entire grid has been traversed in both directions. After completing the sweep, the entire process is repeated in “radio” mode to search for utilities emitting VLF radio signals.

Passive signals enable utilities to be located but not identified, because the same signal may appear on multiple utilities within the grid. To solve this problem, an active signal must be applied to each accessible utility line.

An active signal is one that is intentionally applied to a utility via a transmitter. In this mode, the signal can be applied directly to the utility by direct connection or induction.

This enables utilities to be identified, traced, and their depth to be determined with a receiver.

Direct connection involves plugging a connection cable into a transmitter output socket and connecting directly to the target line. This can be accomplished with connection leads or with a transmitter clamp. Connection leads are generally used to apply a signal to metallic conduits, sight lighting structures, and metallic pipes. This is the preferred method for locating secondary electric, water, and gas.

Many electric, telephone, and cable lines are housed within plastic conduits or buried into the ground without protection. In addition, directly connecting to these lines is usually too risky or forbidden. In such instances, a transmitter clamp is used to apply a signal to the cable without interrupting service to the line. Although the clamp is easy to apply to the target line, the signal usually does not travel as far as when using connection leads, and works best if the target line is grounded at each end .This is the method of choice for locating primary electric, telephone, and cable lines.

If an active signal cannot be applied to a line because it is inaccessible, an induction sweep must be performed. The transmitter houses an antenna that, when placed on the ground directly on top of a utility line, can induce a signal onto it. The advantage of using induction is that a signal can be applied without access to the line and it is very quick and easy to use. The disadvantages are that induction efficiency is poor on deep targets, it is only useful at depths down to 6 feet, and the signal can induce onto lines other than the target. In addition, signal strength is often lost in the surrounding soil, the signal is shielded by reinforced concrete, and a signal will not apply to a well-insulated line unless it is effectively grounded at each end. Despite these shortcomings, an induction sweep can sometimes successfully locate unknown or abandoned utilities when GPR results are inconclusive.

An active signal cannot be applied to non-conductive (non-metallic) utility lines. To work around this limitation, a detectable duct rod or sonde emitting a radio signal must be inserted into the line via a manhole, handhole, cleanout, or catch basin. The disadvantages of this method are that some non-metallic utility lines do not have access points or might be obstructed by detritus. Nonetheless, this is the best method for locating fiber optics, future use conduits, drains, sanitary sewer, and storm sewer.

Ground Penetrating Radar (GPR)

It is quite often the case that non-metallic, inaccessible, unknown, or abandoned utilities cannot be located with a cable and pipe locator. When this situation occurs, GPR must be used in place of it. GPR is a non-invasive, non-destructive geophysical surveying technique that is used to produce a 2-dimensional cross-section image of objects embedded within the subsurface. We currently use the GSSI SIR-3000 and 4000 control units to perform our GPR surveys. This piece of equipment, which is manufactured by Geophysical Survey Systems, Inc. of Nashua, NH, is their latest data acquisition system and the industry’s number one choice for data accuracy and versatility.

All GPR units consist of three main components: a power supply, control unit, and antenna. To understand how these components interact to provide usable data, we must first define a scan. A scan is performed by moving the antenna across the surface linearly to create a series of electromagnetic pulses over a given area. During a scan, the control unit produces and regulates a pulse of radar energy, which is amplified and transmitted into the subsurface at a specific frequency by the antenna.

Antenna frequency is inversely proportional to penetration depth, which makes antenna selection the most important step in the survey design process. Below is a list of antenna frequencies, their application, and maximum penetration depth.

Frequency (MHz)

Sample Applications Max Depth (ft.)

2600 Concrete, Roadways, Bridge Decks

1600 Concrete Roadways, Bridge Decks

1.5

900 Concrete, Shallow Soil, Archaeology

400 Shallow Geology, Utility Locating, Environmental, Archaeology

200 Geology, Environmental 25

100 Geology, Environmental 60

During a scan, the control unit records the strength and time required for the return of any reflected energy. Reflections are produced in the data screen profile (on the control unit) whenever the energy pulse enters and exits contrasting subsurface materials. The way it responds to each material is determined by two physical properties: dielectric constant and electrical conductivity.

The dielectric constant is a descriptive number that indicates how fast electromagnetic energy travels through a material. Energy always attempts to move through a material at the speed of light, but certain materials slow the energy down more than others. The higher the dielectric, the slower the energy will move through the material, and vice versa. Below is a list of some common materials with their corresponding dielectric constants and velocity values.

Material Dielectric Velocity (mm/ns)

Air 1 300

Fresh Water 81 33

Ice 3 167

Dry Sand 3-6 120-170

Wet Sand 25-30 55-60

Silt 10 95

Wet Clay 8-15 86-110

Dry Clay 3 173

Marsh 12 86

Average Soil 16 75

Granite 5-8 106-120

Limestone 7-9 100-113

Concrete 5-8 55-120

Asphalt 3-5 134-173

PVC 3 173

To determine the location of a subsurface target in the data screen profile, there must be a contrast between the dielectric values of the material one is scanning through and the target one is searching for. For example, a pulse moving from dry sand (dielectric of

5) to wet sand (dielectric of 30) will produce a strong, highly visible reflection; while a pulse moving from dry sand (5) to limestone (8) will produce a weak reflection. In addition, if one knows the dielectric value of the subsurface material one is scanning through, the control unit can measure the amount of time required to receive the reflected signal, and this number can be converted to depth.

Since the GPR emits electromagnetic energy, it is subject to attenuation (natural absorption) as it moves through a material. Energy moving through resistive (less conductive) materials such as dry sand, ice, or dry concrete will penetrate much further than energy moving through absorptive (more conductive) materials, such as salt water or wet concrete. As a result of this fact, the greater the contrast in electrical conductivity between the material one is scanning through and the target one is searching for, the brighter the reflection, with high conductive materials such as metals producing the brightest reflections of all.

To understand how dielectric and electrical conductivity differences translate into visual data in the data screen profile requires an understanding of how the antenna emits energy. Imagine the antenna scanning perpendicular to a pipe. Energy emits from the antenna in a 3-dimensional cone shape, not in a straight line as most people think. The two-way travel time for energy at the leading edge of the cone is longer than for energy directly below the antenna. Thus, because it will take longer for energy at the leading edge to be captured, when the antenna first approaches the pipe, it will appear deeper in the data screen profile than the actual depth of the pipe. As the antenna moves closer to the pipe and the distance between them decreases, the reflections will progressively appear higher in the profile. At the point where the antenna is located directly above the pipe, the minimum distance of separation is reached, and the reflections reach their zenith. As the antenna moves away from the pipe and the distance between them progressively increases, the reflections once again appear below the actual depth of the pipe. After the scan is completed, the center of the pipe appears in the data screen profile as an upside down U, or hyperbola.

To gather, organize, and present the data to the client, a series of scans are performed within a 2-dimensional orthogonal survey grid. At the end of each scan, the data screen profile is reviewed for hyperbolic targets. If any are present, the antenna is moved backward, the cursor is moved on top of the center of the target, and a ground marking is made along each side of the center of the antenna. After the entire survey grid has been scanned, the marks are reviewed to search for those that run in a straight line and/or appear to run between two utility structures. Those matching this description are marked with straight arrowed lines using APWA color coded paint and/or flags, thereby indicating the location and depth of underground utilities.

Materials

All cable and pipe locating was performed with an RD8000TL+ and RD8000T10 transmitter, both of which were manufactured by the Radiodetection Corp. of Raymond, ME. The GPR survey was performed with the SIR-4000 control unit in conjunction with a 300/800 MHz antenna, which were manufactured by Geophysical Survey Systems, Inc. of Nashua, NH.

Methods

A visual inspection was performed both within and around the survey area to search for conduits, pipes, clean outs, vaults, handholes, catch basins, valves, vents, and concrete pads. Active mode cable and pipe locating was performed by directly applying a radio signal to all electrical conduits. Passive mode cable and pipe locating was performed to search for inaccessible high voltage electric conduits and telecommunication lines.

Lastly, a GPR survey was performed within the entire survey area to corroborate the results of the cable and pipe locating survey and to search for non-metallic, unknown, and abandoned utilities as well as underground storage tanks (USTs).

Results

Underground utilities were marked on the ground with paint, using the standard American Public Works Association (APWA) color coding system. Electric was marked with red and storm sewer with green. In addition, pink paint was used to mark the location of unknown lines detected with GPR. The results of the survey are shown on the sketch map below.

Discussion

Some of the underground utilities running within the survey area could not be detected with either cable and pipe locator or GPR technology. It is likely that most of the conduits that were unable to be located were encased in concrete or simply empty.

When concrete surrounds a conduit, it can prevent the signal from penetrating through the concrete and back to the receiver. GPR signal penetration was poor throughout most of the survey area, only enabling it to penetrate down to a depth of 3-4 feet.

Another factor reducing the effectiveness of the GPR survey was the lack of space available to make long scans. Therefore, although the utility locating survey was able to reduce some of the risk that will be encountered during drilling, it was unable to eliminate all of it. Due to the foregoing limitations, it is highly recommended that vacuum excavation or hand digging be performed before conventional machine drilling is conducted.

If you have any questions, comments or concerns regarding this report, please don’t hesitate to contact me at 203.313.6431 or svedral@undergroundsurveying.com.

Submitted on December 14, 2022

Stephen Vedral Project Manager mailto:name@undergroundsurveying.com

Appendix 4

Limitations

984 Southford Road Middlebury, CT 06762

(203) 758-8836

Geotechnical Limitations Explorations

1. The analyses and recommendations submitted in this report are based in part upon the data obtained from widely spaced subsurface explorations. The nature and extent of variations between these explorations may not become evident until construction. If variations then appear evident, it will be necessary to reevaluate the recommendations of this report.

2. The generalized soil profile described in the text is intended to convey trends in subsurface conditions. The boundaries between strata are approximate and idealized and have been developed by interpretations of widely spaced explorations and samples; actual soil transitions are probably more erratic. For specific information, refer to the boring logs.

3. Water level readings and moisture conditions have been made in the explorations, and from the samples at times and under conditions stated on the logs. These data have been reviewed and interpretations have been made in the text of this report. However, it must be noted that fluctuations in the level of the groundwater and moisture condition may occur due to variations in rainfall, temperature, and other factors occurring since the time measurements were made.

Review

4. In the event that any changes in the nature, design or location of the proposed structures is planned, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report modified or verified in writing by GEODesign, Inc. We recommend that we be provided the opportunity to review and comment on the finalized project design and relevant construction specifications in order that earthwork and foundation recommendations may be properly interpreted and implemented in the design and specifications.

Use of Report

5. This report has been prepared for the exclusive use of Client, for specific application to the project, as described in GEODesign’s scope of services/ contract and related documents, in accordance with generally accepted soil and foundation engineering practices. No other warranty, express or implied, is made.

6. This report has been prepared for this specific project by GEODesign, Inc. This report is for design purposes only and is not sufficient to prepare an accurate bid. Contractors wishing a copy of the report may secure it with the understanding that its scope is limited to design considerations only, unless otherwise specified in the report.

7. Unless otherwise noted, the scope of our services did not include environmental assessment or investigation for the presence of hazardous or toxic materials in the soil, surface water, groundwater or air, on, below, or around this site.