Appendix C_Geotechnical Data Report.pdf

Chantilly, VA Hampton, VA

Washington, DC Gaithersburg, MD

4170 Lafayette Center Drive, Suite 500, Chantilly, VA 20151 ● www.dmyec.com ● Phone: 703.665.0586 ● Fax: 301.768.4169

GEOTECHNICAL ● CONSTRUCTION ENGINEERING INSPECTION ● SPECIAL INSPECTIONS ● DRILLING ● MATERIALS TESTING ● ENVIRONMENTAL

August 11, 2023 (Revised August 22, 2023)

Mr. Eric Kistner, P.E.

Stantec Consulting Services, Inc 10200 Alliance Road, Suite 300 Blue Ash, Ohio

Reference: Geotechnical Data Report FHWA EFL Mount Vernon Trail in George Washington Memorial Highway Alexandria, Virginia DMY Project No. 01.06114.01; FHWA VA NP GWMP MVT (4)

Dear Mr. Kistner, DMY Engineering Consultants Inc. (DMY) is pleased to submit this geotechnical data report as part of the study for the proposed FHWA EFL Mount Vernon Trail in the George Washington Memorial Parkway project in Alexandria, Virginia (GWMP MVT). Our work was performed according to our proposal with the revision date of April 24, 2023 and authorized on June 15, 2023. This geotechnical data report presents a review of the information provided to us, a discussion of the site and subsurface conditions encountered, our subsurface investigation procedures, and laboratory test results.

Project Description and Site Conditions

The project site is contained entirely within the limits of US Government-owned property of the Mount Vernon Trail near the George Washington Memorial Parkway in Alexandria, Virginia. The project site is bounded by the Potomac River to the east, the George Washington Memorial Parkway to the west, the Tide Lock Park to the south and the Ronald Reagan Washington National Airport to the north. The purpose of this project is to perform a geotechnical investigation for the replacement of four (4) bridges and one (1) boardwalk along the Mount Vernon Trail. A Site Location Map showing the approximate location of the project is included as Figure 1 in Appendix A.

The description of the proposed project given above is based on the information provided to us by the Federal Highway Administration (FHWA) and information gathered during our site reconnaissance. If any of the assumptions or project information is incorrect, DMY should be informed so that we may revise this data report, if necessary.

General Geology

Based on the Geologic Map of the National Parks in the National Capital Region, Washington, D.C., Virginia and West Virginia (2006) published by the USGS, the site lies within the Coastal Plain Physiographic Province of Northern Virginia. More specifically, the geology at the site is described below:

The Potomac Formation (identified as P on the boring logs) consists of light gray to pinkish and greenish gray quartzo-feldspathic sand, fine to coarse-grained, pebbly, poorly sorted, commonly thick-bedded and

FHWA EFL Mount Vernon Trail in the George Washington Memorial Highway, Alexandria, Virginia DMY Project No. 01.06114.01 FHWA VA NP GWMP MVT (4) August 11, 2023 (Revised August 22,2023) trough cross-bedded. The sand is interbedded with gray to green, massive to thick-bedded sandy clay and silt, commonly mottled red or reddish-brown. It includes lesser amounts of clay-clast conglomerate and thin-bedded to laminated, carbonaceous clay and silt. In the inner Coastal Plain, the unit was deposited mainly in fluvial-deltaic environments, intertongues eastward with thin glauconitic sands of shallow-shelf origin. Spore and pollen assemblages and leaf impressions of ferns and cycads indicate an Early Cretaceous age (Doyle and Robbins, 1977). In some downdip areas, the uppermost part of the unit may be of earliest Late Cretaceous age. Thickness ranges from a feather-edge at western limit of outcrop to more than 3500 feet in subsurface of outermost Coastal Plain. Furthermore, the Potomac Formation soils are highly overconsolidated and fissured, and contain pre-existing failure surfaces referred to as "slickensides."

Coastal Plain soils belonging to the Shirley Formation of Quaternary age (identified as C on the boring logs) are present above the Potomac Formation. Constitutes surficial deposits of riverine terraces and relict baymouth barriers and bay-floor plains (altitude 35-45 feet) inset below depositional surfaces of the Chuckatuck Formation (Johnson and Peebles, 1984). Upper part of unit is truncated on the east by the Suffolk and Harpersville scarps; locally, lower part occurs east and west of scarps. Fluvial-estuarine facies comprises (1) a lower pebble to boulder sand overlain by (2) fine to coarse sand interbedded with peat and clayey silt rich in organic material, including in-situ tree stumps and leaves and seeds of cypress, oak, and hickory, which grades upward to (3) medium- to thick-bedded, clayey and sandy silt and silty clay. Marginal-matrix facies in lower James River and lowermost Rappahannock River areas are silty, fine-grained sand and sandy silt containing Crassostrea virginica, Mulinia, Noetia, Mercenaria, and other mollusks. Thickness is 0 to 80 feet.

The youngest natural soils are Alluvium and Fluvial (identified as A on the boring logs) deposits associated with the Potomac River. The soils of this stratum are normally to slightly under-consolidated.

In this area, these soils typically consist of sand interbedded with layers of silt and clay beds and may contain partially decaying wood fragments. Scattered pebbles and cobbles may also be encountered within this stratum.

Existing fill (identified as F on the boring logs) is also present at the site. The soils of this stratum were placed during original site development, or to extend the original riverbank. The soil used to fill the bank may have been imported from the nearby area and may contain rock fragments and other material not present within the geology of the site. No compaction information is available on this fill, which may contain debris, brick fragments, and organic material.

The approximate site location is shown overlayed on the geologic map included as Figure 2 in Appendix A

Field Exploration

The field exploration consisted of drilling six (6) Standard Penetration Test (SPT) borings (BH22-01 through BH22-06). The boring locations were selected by the FHWA and were located in the field by the DMY field engineer utilizing a handheld GPS device. The boring elevations and locations were surveyed after completion by Stantec. The as-drilled boring locations are shown on the Boring Location Plan in Appendix A.

The SPT borings were drilled using a track-mounted CME-55 drill rig (3.25-inch hollow-stem auger with split spoon sampler) per ASTM D1586. Upon completion of drilling, borings were backfilled with auger cuttings and bentonite chips. At the direction of the National Park Service (NPS) and FHWA contact, site restoration and rehabilitation including hand grading, seeding and straw, were performed. Excess auger cuttings were containerized in 55-gal steel drums and disposed of as non-contaminated material. Site photographs that include pictures of the drilling operation and set-up at each boring completion can be found in Appendix A.

Subsurface Conditions

The subsurface conditions encountered at the locations explored are shown on the boring logs and the fence diagram included in Appendix B. The records represent our interpretation of the subsurface conditions in accordance with generally accepted geotechnical engineering practice. The lines designating the interfaces between various strata on the boring logs are approximate, as the actual transitions between soil strata are often gradual. In the absence of foreign substances, it is difficult to distinguish between natural soils and clean soil fills. Although individual test borings are representative of the subsurface conditions at the precise boring locations on the dates shown, they are not necessarily indicative of the subsurface conditions at other locations or at other times.

Approximately 2 inches of topsoil were encountered in the majority of the borings. Topsoil encountered is typically a dark colored soil material containing roots, fibrous matter, and/or other organic components, and is generally unsuitable for engineering purposes. Although the measured topsoil depths were found to be of minimal thickness in the borings during our exploration, the topsoil may be thicker in unexplored areas, particularly in vegetated undisturbed areas. DMY has not performed any laboratory testing to determine the organic content or other horticultural properties of the observed surficial soil material;

therefore, the term topsoil is not intended to indicate suitability for landscaping and/or other purposes.

Four strata were encountered at the borings within their termination depths. The soil strata observed at this site include man-made fill, Alluvium, Coastal Plain deposits, and Potomac Formation. The following table summarizes the generalized soil descriptions from the available subsurface exploration.

Table 1. Summary of Subsurface Conditions Geologic

Strata (On Boring

Log)

Soil Description Visual Classification SPT N-values Elevation (ft)

Primary Secondary Min Max Min Max

Fill (F2 & F3)

Generally composed of soils obtained from nearby natural soils or imported to the site. The soils from this stratum generally retain some of the properties of the parent soil, but may contain debris, organic material and gravel.

SM SC-SM, CL 4 29 0.8 10.8

(GS)*

Alluvium (A2 & A3)

Alluvium and Fluvial deposited by flowing streams in a river valley or delta. The soils of these strata are loose, unconsolidated soils or sediments, which has been eroded, reshaped by water in some form, and redeposited in a non-marine setting.

SM, CL ML-CL, ML WOH* 27 -26.9 3.5

Coastal Plain

Deposits (C2 & C3)

Coastal Plain deposits that belong to the Quaternary Age Shirley Formation.

SM ML WOH 55 -43.9 -8.5

Potomac (P1 & P3)

Coastal Plain soils that belong to the Potomac Formation.

SM, CH SP-SM 7 50/4 -39.6 8.4

*WOH: Weight of Hammer *GS: Ground Surface

Groundwater readings were obtained during drilling and at the completion of drilling in each boring. The groundwater readings are summarized in Table 2 below. It should be noted that groundwater levels fluctuate with seasonal and climatic variations and may be different at other times and locations than those stated in this report.

Table 2. Summary of Groundwater Readings

Boring Depth of Water at Time of Drilling (ft)

Depth of Water at Drilling Completion

(ft)

BH22-01 12 8

BH22-02 10 7

BH22-03 Not Encountered Not Encountered

BH22-04 Not Encountered Not Encountered

BH22-05 10 9

BH22-06 14 17.5

Laboratory Testing

Representative soil samples were selected and tested in the laboratory to verify field classifications and to determine pertinent engineering properties. The table below is a summary of the laboratory testing program. Laboratory results are included in Appendix C.

Table 3. Summary of Laboratory Tests Lab Test Test Method Number of Tests

Natural Moisture Content ASTM D2216 19

Atterberg Limits ASTM D4318 19

Sieve with Wash No. 200 ASTM D2487 19 pH AASHTO T-289 2

Resistivity AASHTO T-288 2

Chloride AASHTO T-291 2

Sulfate AASHTO T-290 2

August 11, 2023 (Revised August 22,2023)

Limitations

The boring logs included in this report depict the subsurface soil and groundwater conditions at the specific locations where the borings were performed. Regardless of the thoroughness of a subsurface investigation, there is always a possibility that subsurface conditions may vary from those documented during a subsurface exploration at specific locations. We have prepared this data report in accordance with generally accepted geotechnical engineering practices. No other warranty, expressed or implied, is made as to the professional advice included in this report.

Closure

We appreciate the opportunity to be of service to you on this project and please do not hesitate to contact the undersigned if you have any questions or need additional assistance.

Respectfully, DMY ENGINEERING CONSULTANTS INC.

Felix Rivera Santiago, M.S. Rabih Khouri, P.E.

Geologist Principal Engineer

Attachments:

Appendix A Site Location Map Site Geologic Map Boring Location Plan and Site Photos

Appendix B Field Procedures, Reference Notes and USCS Chart Boring Logs and Fence Diagrams

Appendix C Laboratory Testing Results

Digitally signed by Felix Rivera Santiago Date: 08/23/23

Felix Rivera Santiago

Digitally signed by rabih A khouri Date: 08/22/23

Appendix A Figures and Site Photos

COPYRIGHT GOOGLE

FHWA EFL GWMP MVT (4)

Alexandria, Virginia

DATE:

08/21/2023

SCALE:

1"=2000'

DRAFTED BY:

RAK

CHECKED BY:

PZ

PROJECT NO.:

01.06114.01

FIGURE NO.:

DMY ENGINEERING CONSULTANTS INC.

4170 LAFAYETTE CENTER, SUITE 500

CHANTILLY, VIRGINIA 20151

PHONE: (703) 665-0586

FAX: (301) 768-4169

SITE LOCATION MAP

COPYRIGHT US GEOLOGIC SURVEY

FHWA EFL GWMP MVT (4)

Alexandria, Virginia

DATE:

08/21/2023

SCALE:

1"=2000'

DRAFTED BY:

RAK

CHECKED BY:

PZ

PROJECT NO.:

01.06114.01

FIGURE NO.:

DMY ENGINEERING CONSULTANTS INC.

4170 LAFAYETTE CENTER, SUITE 500

CHANTILLY, VIRGINIA 20151

PHONE: (703) 665-0586

FAX: (301) 768-4169

SITE GEOLOGIC MAP

PROJECT NAME: FHWA EFL GWMP MVT (4)

PROJECT NO.: 01.06114.01

LOCATION: Alexandria, VA CLIENT: Stantec/FHWA

PHOTOGRAPH LOG

PHOTO #: DATE: DESCRIPTION:

07/03/2023 View of boring BH22-01 looking north before drilling.

PHOTO #: DATE: DESCRIPTION:

2 07/03/2023 View of boring BH22-01 looking north during drilling.

LOCATION: Alexandria, VA CLIENT: Stantec/FHWA

PHOTOGRAPH LOG

PHOTO #: DATE: DESCRIPTION:

3 07/03/2023 View of boring BH22-01 looking north after drilling.

4 07/05/2023 View of boring BH22-02 looking south before drilling.

LOCATION: Alexandria, VA CLIENT: Stantec/FHWA

PHOTOGRAPH LOG

PHOTO #: DATE: DESCRIPTION:

5 07/05/2023 View of boring BH22-02 looking south during drilling.

6 07/05/2023 View of boring BH22-02 looking north after drilling.

LOCATION: Alexandria, VA CLIENT: Stantec/FHWA

PHOTOGRAPH LOG

PHOTO #: DATE: DESCRIPTION:

7 07/10/2023 View of boring BH22-03 looking south before drilling.

8 07/10/2023 View of boring BH22-03 looking north during drilling.

LOCATION: Alexandria, VA CLIENT: Stantec/FHWA

PHOTOGRAPH LOG

PHOTO #: DATE: DESCRIPTION:

9 0710/2023 View of boring BH22-03 looking north after drilling.

10 07/07/2023 View of boring BH22-04 looking south before drilling.

LOCATION: Alexandria, VA CLIENT: Stantec/FHWA

PHOTOGRAPH LOG

PHOTO #: DATE: DESCRIPTION:

11 07/07/2023 View of boring BH22-04 looking north during drilling.

12 07/07/2023 View of boring BH22-04 looking south after drilling.

LOCATION: Alexandria, VA CLIENT: Stantec/FHWA

PHOTOGRAPH LOG

PHOTO #: DATE: DESCRIPTION:

13 07/06/2023 View of boring BH22-05 looking north before drilling.

14 07/06/2023 View of boring BH22-05 looking north during drilling.

LOCATION: Alexandria, VA CLIENT: Stantec/FHWA

PHOTOGRAPH LOG

PHOTO #: DATE: DESCRIPTION:

15 07/06/2023 View of boring BH22-05 looking south after drilling.

16 07/12/2023 View of boring BH22-06 looking north before drilling.

LOCATION: Alexandria, VA CLIENT: Stantec/FHWA

PHOTOGRAPH LOG

PHOTO #: DATE: DESCRIPTION:

17 07/12/2023 View of boring BH22-06 looking north during drilling.

18 07/12/2023 View of boring BH22-06 looking west after drilling.

Appendix B Field Exploration

SUBSURFACE EXPLORATION PROCEDURES

Soil Borings – Hollow Stem Auger

In hollow stem auger drilling, the drill rig utilizes continuous flight, hollow stem (center opening ranges from 2-1/4 to 4-1/4 inches in size) augers to advance the boreholes. During drilling or formation cutting, the center of the hollow augers is filled with rods connected to a plug at the bottom bit. Once the desired drilling depth is reached, the center plug and rods can be pulled out, leaving the hollow augers in place to hold the borehole open for sampling and well installation. Sampling is performed through the center opening in the hollow stem augers by means of the split-barrel sampling procedure in accordance with ASTM D1586. Usually, drilling fluid is not used during the soil drilling using this procedure.

Standard Penetration Tests

In this process, a 2 foot long, 2 inch outside-diameter split-barrel sampler attached to the end of a string of drilling rods is driven 18 inches into the ground by successive blows of a 140 pound hammer freely dropping 30 inches. The number of blows needed for each 6 inches of penetration is recorded. The blows required for the first 6 inches of penetration are allowed for seating the sampler into any loose cuttings, and the sum of the blows required for penetration of the second and third 6 inch increments constitutes the standard penetration resistance or N-value. After the test, the sampler is extracted from the ground and opened to allow visual examination and classification of the retained soil sample. The N-value can be used as a qualitative indication of the in-place relative density of cohesionless soils (sands). In a less reliable way, it also indicates the consistency of cohesive soils (clays/silts). This indication is qualitative, since many factors can significantly affect the N-value and prevent a direct correlation among drilling crews, drill rigs, drilling procedures, and hammer-rod-sampler assemblies. The N-value also has been empirically correlated with various soil properties including strength, compressibility and potential for difficult excavation.

REFERENCE NOTES FOR BORING LOGS

I. Drilling and Sampling Symbols:

SS - Split Spoon Sampler RB - Rock Bit Drilling ST - Shelby Tube Sampler BS - Bulk Sample of Cuttings RC - Rock Core; NX, BX, AX PA - Power Auger (no sample) PM - Pressuremeter HSA - Hollow Stem Auger DC - Dutch Cone Penetrometer WS - Wash Sample

Standard Penetration Test (SPT) resistance refers to the blows per foot (bpf) of a 140 lb hammer falling 30 inches on a 2 in. O.D. split-spoon sampler as specified in ASTM D-1586. The blow count is commonly referred to as the N-value.

II. Correlation of Penetration Resistances to Soil Properties:

Relative Density of Cohesionless Soils Consistency of Cohesive Soils

SPT-N (bpf) Relative Density SPT-N (bpf) Consistency

0 – 3 Very Loose 0 – 1 Very Soft 4 – 9 Loose 2 – 4 Soft 10 – 29 Medium Dense 5 – 8 Firm 30 – 50 Dense 9 – 15 Stiff >50 Very Dense 16 – 30 Very Stiff

31 – 50 Hard >50 Very Hard

Weathered Rock (WR) may be defined as SPT-N values exceeding 60 bpf depending on site specific conditions. Refer carefully to boring logs.

Rock Fragments, gravel, cobbles, boulders, or debris may produce N-values that are not representative of actual soil properties.

III. Unified Soil Classification Symbols:

GP – Poorly Graded Gravel ML – Low Plasticity Silts GW – Well Graded Gravel MH – High Plasticity Silts GM – Silty Gravel CL – Low Plasticity Clays GC – Clayey Gravels CH – High Plasticity Clays SP – Poorly Graded Sands OL – Low Plasticity Organics SW – Well Graded Sands OH – High Plasticity Organics SM – Silty Sands CL-ML – Dual Classification (Typical) SC – Clayey Sands

IV. Laboratory Testing and Water Level Symbols:

LL – Liquid Limit (%) Water Level at Time of

Drilling, or as Shown

Water Level at End of Drilling, or as Shown

Water Level after 24 Hours, or as Shown

PI – Plastic Index (%) W – Moisture Content (%) DD – Dry Density (PCF) NP – Non Plastic -200 – Percent Passing No. 200 Sieve PP – Pocket Penetrometer (TSF)

UNIFIED SOIL CLASSIFICATION SYSTEM (ASTM D-2487)

MAJOR DIVISIONS GROUP

SYMBOL TYPICAL NAMES LABORATORY CLASSIFICATION CRITERIA

CO

AR

SE

-G

RA

IN

ED

S

O

IL

S (L es s th an

0% p as se s

N o.

S ie ve s iz e)

G

RA

VE

LS

(5

0% o r l es s of c oa rs e fra ct io n is pa ss es

N o.

si ev e)

CL

EA

N

G

RA

VE

LS

(L es s th an p as se s

N o.

s ie ve ) GW Well-graded gravels, gravel-sand mixtures, little or no fines Cu = D60/D10 greater than 4

Cc = (D30)2/(D10xD60) between 1 and 3

GP Poorly graded gravels, gravel-sand mixtures, little or no fines Not meeting all gradation requirements for GW

G

RA

VE

LS

W

IT

H F

IN

ES

(M or e th an

2% p as se s

N o.

s ie ve ) GM Silty gravels, gravel-sand mixtures Atterberg limits below “A” line or P.I. less than 4 Above “A” line with P.I. between 4 and 7 are borderline cases requiring use of dual symbols

GC Clayey gravels, gravel-sand-clay mixtures

Atterberg limits below “A” line or P.I. less than 7

SA

ND

S (M or e th an

0% o f c oa rs e fra ct io n pa ss es

N o.

si ev e)

CL

EA

N

SA

ND

S

(L es s th an p as se s N o.

s ie ve

) SW Well-graded sands, gravelly sands, little or no fines

Cu = D60/D10 greater than 6 Cc = (D30)2/(D10xD60) between 1 and 3

SP Poorly graded sands, gravelly sands, little or no fines Not meeting all gradation requirements for SW

SA

ND

S W

IT

H

F

IN

ES

(M or e th an

2% pa ss es N o.

s ie ve

SM Silty sands, sand-silt mixtures Atterberg limits above “A” line or P.I. less than 4

Limits plotting in CL-ML zone with P.I.

between 4 and 7 are borderline cases requiring use of dual symbols

SC Clayey sands, sand-clay mixtures Atterberg limits above “A” line with P.I. greater than 7

FI

NE

-G

RA

IN

ED

S O

IL

S

(5 0% o r m or e pa ss es N o.

S ie ve

SI

LT

S

AN

D

CL

AY

S

(L iq ui d lim it le ss th an

0)

ML

Inorganic silts and very fine sands, rock flour, silty or clayey fine sands, or clayey silts with slight plasticity

DEGREE OF PLASTICITY OF COHESIVE SOILS

Degree of Plasticity Plasticity Index None to Slight 0-4 Slight 5-7 Medium 8-22 High to Very High Over 22

CL

Inorganic clays of low to medium plasticity, gravelly clays, sandy clays

OL Organic silts and organic silty clays of low plasticity

SI

LT

S

AN

D

CL

AY

S

(L iq ui d lim it gr ea te r t ha n

MH

Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts

CH Inorganic clays of high plasticity, fat clays

OH Organic clays of medium to high plasticity, organic silts

HI

G

HL

Y

O

RG

AN

IC

SO

IL

S

Pt Peat and other highly organic soils

0 10 20 30 40 50 60 70 80 90 100

Pl as tic ity

In de x

Liquid Limit

PLASTICITY CHART

"A" line CH or OH

MH or OH

CL or OL

ML or OL

CL-ML

Appendix C Laboratory Results

R es

=5

O hm

-c m

La b or at or y

C or ro si vi ty

T es tin g

Ja y K ay Te sti ng

, I nc

FH

W

A

EF

L G

W M

P M

VT

(4

P ro je ct N um be r:

1.

4.

O R

P ²

S ul fid e⁵

A S

T M

D -1

M et hy le ne T itr at io n

B H

-0

S

7- S

7.

.2

,5

6, ,0

0.

B H

-0

S

6- S

6.

.1

7, 0.

¹ pH v er ifi ed w ith s ec on d pH m et er

² O

R P e le ct ro de . V er ifi ed w ith s ep ar at e

O R

P m et er

³ V er ifi ed w ith s ep ar at e ch lo ri de p ho to m et er m et ho d.

⁴ T ur bi d im et ri c p ho to m et er m et ho d

. V er ifi ed w ith s ep ar at e tu rb id im et ri c tit ra tio n m et ho d.

A ll di lu tio ns a re

:1 e xc ep t s ul fa te , 3

:1 pe r m et ho d)

⁵ P om er oy m et hy le ne b lu e m et ho d tit ra tio

n) . V er ifi ed w ith a s ep ar at e m et ho d us in g au to

-d ilu tio n am po ul es fo r co lo ri m et ri c an al ys is

S am pl e

ID

Chlorides, μg/kg (1:1)

Sulfates, PPM (mg/kg) (3:1)

Sulfates, % Dry Weight (3:1) pH ¹

R es is tiv ity C hl or id e³

S ul fa te

⁴

Boring ID

Sample ID A

A S

H T

O T

-2

A A

S H

T O

T -2

A

A S

H T

O T

-2

D ep th

/2

5/

T es te d by

S T

/J T

R ev ie w ed b y:

F

R S

E 2C

R

Sulfides Ion Presence (1:1) pH (1:1)

Test Temperature, °C

Chlorides, PPM (mg/kg) (1:1)

Remarks

Top, ft

Bottom, ft

Natural Water Content, %

ORP (Redox), mV (1:1)

(8

4-

D

C

M D

, P A

, V A w w w .ja yk ay te st in g.

co m

A A

S H

T O

T -2

As Received, Ω-cm

Minimum, Ω-cm

Saturated, Ω-cm