Prepared for

CDM Smith

August 25, 2024 (Revised October 17,2024;

revised December 11, 2024)

Geotechnical Investigation Report

WSSC Anacostia WWPS Surge Tanks Removal

Capitol Heights, Maryland

DMY Proposal No. 03.06675.01

Chantilly, VA

Williamsburg, VA

Washington, DC

Gaithersburg, MD

7917 Cessna Avenue, Unit L, Gaithersburg, MD 20879 ● www.dmyec.com ● Phone: 301.768.4168 ● Fax: 301.768.4169

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

August 25, 2024 (Revised October 17, 2024; revised December 11, 2024)

Mrs. Mary Vahdati, PMP

Project Manager

CDM Smith

10306 Eaton Place, Suite 220, Fairfax, Virginia 22030

Reference: Geotechnical Engineering Report

WSSC Anacostia WWPS Surge Tanks Removal

Capitol Heights, Maryland

DMY Project No. 03.06675.01

Dear Mrs. Vahdati:

DMY Engineering Consultants Inc. (DMY) is pleased to submit our geotechnical report for the above-referenced project. The study was performed in accordance with our proposal dated January 21, 2024, and authorized by you on April 29, 2024. The scope of this study involved reviewing project information, conducting Standard Penetration Testing (SPT) borings at two locations, performing laboratory tests on soil samples, and evaluating the collected data to provide recommendations for excavation, dewatering, backfill, and quality assurance. The field exploration revealed surficial topsoil, overlaying fill materials and coastal deposit soils. Groundwater was encountered at depths ranging from 8.2 to 8.4 feet below the surface during drilling, highlighting the need for careful groundwater management during construction.

Based on the findings, open excavation with backfill is recommended for tank demolition, with sloping or temporary supports as required by OSHA and WSSC standards. Dewatering system may be necessary to manage groundwater and maintain site stability. Only suitable materials, such as specific sand and fine-grained soils, should be used for backfill, while high plasticity and organic soils should be removed. To ensure compliance with specifications and best practices, a full-time geotechnical inspector should oversee all demolition and backfill operations.

We will store the boring samples for a period of 90 days from the date of this letter. At the end of the holding period, the samples will be discarded unless you request otherwise. We appreciate the opportunity to be of service to you on this project and would be happy to discuss our findings with you.

We look forward to serving as your geotechnical engineer on the remainder of this project and on future projects.

Respectfully, DMY ENGINEERING CONSULTANTS INC.

Assefa Melorie, Ph.D. Xin Chen, Ph.D., M.B.A., P.E.

Staff Geotechnical Engineer Vice President

WSSC Anacostia WWPS Surge Tanks Removal, Capitol Heights, Maryland

TABLE OF CONTENTS

1.0 PROJECT OVERVIEW

1.1. PROJECT INFORMATION AND SITE CONDITIONS

1.2. SCOPE OF SERVICES

2.0 FIELD EXPLORATION AND LABORATORY TESTING

2.1. FIELD EXPLORATION

2.2. LABORATORY TESTING

3.0 SITE GEOLOGY AND SUBSURFACE CONDITIONS

3.1. SITE GEOLOGY AND SOIL SURVEY MAP

3.2. SUBSURFACE CONDITIONS

4.0 GEOTECHNICAL EVALUATION AND RECOMMENDATIONS

4.1. EXCAVATION CONSIDERATION

4.2. ABANDONMENT CONSIDERATION

4.3. DEWATERING CONSIDERATION

4.4. BACKFILL AND COMPACTION CONSIDERATIONS

4.5. MONITORING AND QUALITY ASSURANCE

5.0 LIMITATIONS

APPENDIX A FIGURES

APPENDIX B FIELD OPERATIONS AND RESULTS

APPENDIX C LABORATORY TESTING

1.0 PROJECT OVERVIEW

1.1. PROJECT INFORMATION AND SITE CONDITIONS

The project site is located at 4200 Andalusia Ln, Capitol Heights, MD. Figure 1 in Appendix A shows the project location. The specific work site is located south of Anacostia Wastewater Pumping Station No.2 and currently occupied by eight surge tanks, trees, and driveway. The project site is bordered by

Beaverdam Creek to the north, by wooded area in the District of Colombia to the west and southwest, and Anacostia Fwy to southeast and east.

According to the information provided to us by CDM Smith (herein referred to as "Client"), we understand that the project task includes full demolition of the surge tanks at Anacostia Wastewater Pumping Station

(WWPS) 2 in accordance with the applicable WSSC Water Pipeline Design Manual and standard specifications. The surge tanks were originally built based on the assumption that Anacostia II WWPS would pump flows to the Piscataway Wastewater Treatment Plant. But the tanks are no longer in use due to significant corrosion on the structures which has raised safety concerns and prompting the need for their removal.

Based on the as-built information dated 1976 for the existing development provided by the client, the eight (8) surge tanks occupy south of the Anacostia Pumping Station No.2 and measures about 233 square feet in surface area. The bottom of the tank slab is at about EL. 2.0 ft and the invert of tank at about EL. 10.0 ft. The surge tank roof top is at about EL. 60.5 ft. The site is partially wooded at south and west corners. According to this plan, the tank slab is underlain by a minimum of 6 inches compacted aggregates.

The description of the proposed project given above is based on the information provided to us by client 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 our geotechnical recommendations, if necessary.

1.2. SCOPE OF SERVICES

The purposes of this study is to obtain the subsurface information and groundwater information for the proposed project. In accordance with our proposal dated January 21, 2024, our scope of services included the following:

• Review the project information provided to us;

• Perform Standard Penetration Testing (SPT) borings at two (2) locations;

• Perform laboratory tests on selected soil samples.

• Evaluate field and laboratory data;

• Prepare this geotechnical engineering report.

2.0 FIELD EXPLORATION AND LABORATORY TESTING

2.1. FIELD EXPLORATION

The field exploration consisted of two (2) Standard Penetration Test (SPT) borings (SB-1 and SB-2). The boring locations were selected by the Client and located in the field by a DMY field engineer based on the information provided by the Client and the existing site conditions (e.g. access, utilities, etc.). The approximate boring locations are shown on the Boring Location Plan included as Figure 2 in Appendix A.

The SPT borings were drilled by a truck-mounted CME-55 drill rig (3.25-inch hollow-stem auger with split spoon sampler) per ASTM D1586. Each SPT boring was drilled up to the termination depth ranging from

20 ft to 25-ft below the existing ground. The SPT borings were performed continuously in the top 10 feet, then at 5-ft interval to the scheduled boring depth. Groundwater levels were measured at each boring location during drilling and upon drilling completion. DMY backfilled the boreholes after completion of drilling. As a result, we did not obtain 24-hour groundwater readings. Upon completion of the field exploration, all SPT borings were backfilled with auger cuttings. The field exploration procedures and the boring logs are included in Appendix B.

Following field operations, the soil samples were transported to the laboratory for further review and testing. The samples will be stored in the laboratory for a period of ninety (90) days from the submittal date of this report. After this period, the samples will be discarded unless we are instructed otherwise.

2.2. LABORATORY TESTING

Representative jar samples of soils collected from the split spoon sampler were selected and tested in the laboratory to verify the field identification and determine pertinent engineering properties. The laboratory testing results are included in Appendix C of this report.

The laboratory testing program included the following:

• Natural moisture Content (ASTM D2216) 6 Tests

• Grain size analysis (ASTM D422) 6 Tests

• Atterberg Limits (ASTM D4318) 5 Tests

• Standard Proctor (ASTM D698) 2 Test

3.0 SITE GEOLOGY AND SUBSURFACE CONDITIONS

3.1. SITE GEOLOGY AND SOIL SURVEY MAP

According to the Physiographic Provinces Map of Maryland published by the Maryland Geological Survey

Geologic map of Maryland (1968), the project site is located within the Atlantic Coastal Plain Province in the Western Shore Uplands Region. The Atlantic Coastal Plain Province is a Physiographic Province of the larger Anacostia Valley Area, bounded between the fluvial terraces to the west and the Atlantic

Seaboard fall line to the east. The geological unit at the project site is mapped as the Lowland Deposits.

The Lowland Deposits comprise of clay, silt, and medium- to coarse-grained sand and gravel. cobbles and boulders are found near the base and commonly contains reworked Eocene glauconite. Much of these sediments are varicolored silts and clays and brown to dark gray lignitic silty clay. This lowland ecosystem contains estuarine to marine fauna in some areas (includes in part Pamlico, Talbot, Wicomico and Sunderland Formations of earlier reports). The thickness of the sedimentary deposits above bedrock in this region ranges from 0 to 150 feet.

According to the Natural Resources Conservation Service Web Soil Survey (NRCS) of Prince George’s

County, the surficial soils in the project area dominantly consist of Fallsington sandy loams and Urban land-Russett-Christiana. The following summarizes the characteristics of the dominant soil unit at the project site area:

FaaA—Fallsington sandy loams: This soil unit has Drainage of poorly drained. A typical profile of this soil unit is listed below:

• Ap - 0 to 10 inches: sandy loam

• Btg - 10 to 32 inches: sandy clay loam

• BCg - 32 to 39 inches: loamy sand

• Cg1 - 39 to 46 inches: sandy clay loam

• Cg2 - 46 to 80 inches: sand

UrrB— Urban land complex: This soil unit has Runoff classifications of very high and Hydrologic soil group D.

UrrB— Russett complex: This soil unit has Drainage and Runoff Classification of moderately well drained and low, respectively. A typical profile of this soil unit is listed below:

• A - 0 to 4 inches: fine sandy loam

• Bt1 - 4 to 7 inches: loam

• Bt2 - 7 to 13 inches: loam

• Bt3 - 13 to 46 inches: clay loam

• BCg1 - 46 to 57 inches: sandy clay loam

• BCg2 - 57 to 77 inches: silty clay loam

UrrB— Christiana complex: This soil unit has Drainage and Runoff Classification of moderately well drained and medium, respectively. A typical profile of this soil unit is listed below:

• A - 0 to 4 inches: fine sandy loam

• Bt1 - 4 to 7 inches: loam

• Bt2 - 7 to 13 inches: loam

• Bt3 - 13 to 46 inches: clay loam

• BCg1 - 46 to 57 inches: sandy clay loam

• BCg2 - 57 to 77 inches: silty clay loam

3.2. SUBSURFACE CONDITIONS

The subsurface conditions encountered at the locations explored are shown in the boring logs 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 fill materials. Although individual test borings are representative of the subsurface conditions at the boring locations on the dates shown, they are not necessarily indicative of the subsurface conditions at other locations or at other times. Below is a summary of the subsurface conditions encountered during our field exploration:

Surficial Materials

Approximately 3 to 5 inches of topsoil were encountered in all borings. Topsoil encountered was typically a dark- colored soil material containing roots, fibrous matter, and/or other organic components, and is generally unsuitable for engineering purposes. 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.

Stratum I, Existing Fill

Existing fill materials classified as CLAYEY SAND WITH GRAVEL (SC), SILTY CLAYEY SAND WITH

GRAVEL (SC-SM), SILTY SAND WITH GRAVEL (SM), and POORLY GRADED SAND WITH SILT AND

GRAVEL (SP-SM) were encountered in all borings. This stratum was present beneath the surficial material and extended to depths ranging from 5 to 18.0 feet below current site grades.

Stratum II, Coastal Deposit Soils

Coastal Deposit soils were encountered beneath the existing fill materials in all borings. This stratum was encountered to each boring’s termination depth. These soils were classified as LEAN CLAY (CL), SANDY

LEAN CLAY (CL), CLAYEY SAND (SC), CLAYEY SAND WITH GRAVEL (SC), POORLY GRADED

SAND WITH SILT and GRAVEL(SP-SM), and POORLY GRADED SAND WITH GRAVEL (SP).

Groundwater

Groundwater was encountered within the borings as shown in Table 3-1 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 3-1: Summary of Groundwater Levels

Boring

ID

Boring Depth (feet)

Groundwater Level (feet below the existing grades)

During drilling After completion 24 hours after completion

SB-1 25 13.0 8.2 Not measured

SB-2 20 13.0 8.4 Not measured

4.0 GEOTECHNICAL EVALUATION AND RECOMMENDATIONS

4.1. EXCAVATION CONSIDERATION

We understand that the demolishing of the existing surge tanks may use open excavation with backfill operation. The existing surge tank total depth is about 16.0 feet below the existing ground. If open excavation is to be utilized, the excavations shall be sloped per requirements of Trenching and

Excavation Safety (OSHA 2226-10R 2015). For excavations deeper than 4 feet or in areas where sloping is not possible due to site constraints or any other reason(s), temporary support of excavation should be required and performed in accordance with the Washington Suburban Sanitary Commission (WSSC)

Standard Specification Section 02315 Part 3.

Stockpiles should NOT be kept near the excavation area to avoid surcharging and its location should be approved by designated Engineer to avoid contamination and prevent erosion. The Contractor should submit working drawings and calculations for design of the temporary excavation support systems, signed and sealed by the Contractor’s Professional Engineer licensed to practice in the State of Maryland.

The working drawings and calculations should be submitted to the Engineer for review. The Contractor should be entirely responsible for the design and adequacy of the temporary excavation support systems.

All waste material generated during demolition, including excavated soil and groundwater, as applicable, must be characterized for appropriate disposal and/or reuse options. If the excavated material is considered contaminated (such as the presence of spilled oil), its disposal should be in accordance with the WSSC Pipe Design Manual Part 3, Section 24 C.

4.2. DEWATERING CONSIDERATION

Groundwater was encountered above or near the existing structures bottom depth during our subsurface exploration, it should be noted that groundwater may still be present at the locations and/or depths not indicated from the borings since 24-hour groundwater readings were not obtained due to public safety concerns. It should also be noted that fluctuations in the groundwater level and perched water conditions can occur seasonally due to variations in precipitation, surface runoff, construction activity, and other site-specific factors.

Dewatering and drainage should be performed in accordance with WSSC Standard Specification Section

02315 Part 3.1.G. The site should be graded to direct surface runoff away from the excavations. It is the responsibility of the Contractor to prepare for, design, and implement a dewatering and drainage system that maintains a stable, undisturbed subgrade that is free from groundwater and surface water during all construction operations. In case wet weather is encountered, the Contractor should take care to schedule excavations to limit the duration of open cuts, slope the bottoms of the excavations to facilitate drainage and provide berms to limit runoff into the excavations. The Contractor shall be prepared to operate the dewatering system continuously. During periods where failure of the system would adversely impact work completed, the Contractor shall provide a back-up system to ensure continuous operations. The

Contractor shall design the dewatering system to not adversely impact adjacent structures or site features.

The actual extent of the dewatering system shall be determined at the time the excavation is performed.

4.3. BACKFILL AND COMPACTION CONSIDERATIONS

General Trench Backfill materials should be suitable material classified as GW, GP, SW, SP, GM, GC, GW-GC, SP-SM, SM, SC, or SW, or the inorganic fine-grained soils with less than 30% retained on No.

200 sieve classified as ML or CL. High plasticity fine-grained soils classified as MH or CH and organic soils classified as OL, OH and PT should be classified as unsuitable and should be removed from the site. Based on the subsurface conditions observed in our exploration, the majority of the onsite natural soils and fill materials consist of SAND with various amounts of clay, silt and gravel may be re-used as

General Trench Backfill. The backfill and compaction shall be performed in accordance with WSSC

Standard Specifications Section 02315 – Earthwork for Pipeline Construction.

4.4. MONITORING AND QUALITY ASSURANCE

The demolition or abandonment of the structures shall be performed, inspected, and tested per WSSC

Standard Specifications and WSSC Common Design Guidelines. We recommend a full-time inspector under the supervision of a geotechnical engineer should be on site during the demolition. Deviations, either from specifications or good construction practice, should be brought to the attention of the concerned authority, along with appropriate recommendations. Before field operations begin, a representative sample of each proposed backfill material should be collected and tested to determine its

Atterberg Limits, gradation, maximum dry density, optimum moisture content, and natural moisture content. The test results will be used to evaluate the suitability of each proposed backfill for quality control purposes during fill placement.

5.0 LIMITATIONS

The recommendations provided are based in part on project information provided to us and are only applied to the specific project and site discussed in this report. If the project information section in this report contains incorrect information or if additional information is available, DMY should be contacted to review our recommendations. We can then modify our recommendations for the proposed project.

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. In addition, the tank demolition process itself may alter subsurface conditions. Therefore, experienced geotechnical personnel should be engaged to observe and document the demolition and restoration procedures used and the conditions encountered. Unanticipated conditions and inadequate procedures should be reported to the design team along with timely recommendations. We recommend that DMY be retained to provide this service based upon our familiarity with the project, the subsurface conditions, and the intent of the recommendations.

We have prepared this report for use by the design professionals for design purposes 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.

APPENDIX A FIGURES

COPYRIGHT GOOGLE

WSSC ANACOSTIA WWPS SURGE TANKS REMOVAL

CAPITOL HEIGHTS, MD 20743

DATE:

08/15/2024

SCALE:

NTS

DRAFTED BY:

AM

CHECKED BY:

XC

PROJECT NO.:

03.06675.01

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

AutoCAD SHX Text N

NOTE: THERE ARE SMALL 1"± LINES

INSIDE THIS SHAFT 12'± DEEP.

Estimated As-drilled Boring Location

SB-2

SB-1

APPENDIX B FIELD OPERATIONS AND RESULTS

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

C O

A R

S E

-G R

A

IN

E D

S O

IL

S

(L e s s t h a n p a s s e s N o

S ie v e s iz e ) G

R A

V E

L

(5 o r le s s o f c o a rs e f ra c ti o n i s p a s s e s N o s ie v e

C L

E A

N G

R A

V E s s t h a n p a s s o s ie v e

) 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 R

A V

E L

S W

IT

H

F

IN

E

(M re t h a n p a s s s ie v e

) 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

S A

N D re t h a n o f c o a rs e f ra c ti o n p a s s e s N o ie v e

C L

E A

N S

A N s s t h a n p a s s s ie v e

) 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

S A

N D

S W

IT

H

F

IN

E re t h a n p a s s e s N o s ie v e

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

F

IN

E -G

R A

IN

E

D S

O

(5 o r m o re p a s s e s N o S ie v e

S

IL

T S

A N

D C

L A

Y iq u id l im it l e s s t h a n

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

S

IL

T S

A N

D C

L A u id l im it g re a te r th a 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

H

IG

H

O R

G A

IC

Pt Peat and other highly organic soils

0 10 20 30 40 50 60 70 80 90 100

P la s ti c it y I n d e x

Liquid Limit

PLASTICITY CHART

"A" line CH or OH

MH or OH

CL or OL

ML or OL

CL-ML

0.4

8.0

13.0

18.0

19.5

24.0

25.0

5-in Topsoil Moist, Brown and Gray, Medium Dense to Dense, Fine To Coarse, SILTY

SAND WITH GRAVEL

(SM), Contains Trace Roots, (FILL) Same, Mottled

Moist, Dark Brown, Medium Dense, Fine To Coarse, POORLY GRADED SAND

WITH SILT AND

GRAVEL(SP-SM ), (FILL)

Wet, Brown, Loose, Fine To Coarse, CLAYEY SAND

WITH GRAVEL(SC), (FILL)

Wet, Light Gray and Brown, Loose, Fine To Coarse, POORLY GRADED SAND

WITH GRAVEL(SP),

Contains Trace Clay, (COASTAL DEPOSIT)

Moist, Gray,Firm to Stiff, SANDY LEAN CLAY (CL), (COASTAL DEPOSIT)

Moist, Molted, Stiff, LEAN

CLAY (CL), (COASTAL

DEPOSIT)

BOTTOM OF HOLE

(TERMINATED)

Bulk sample was collected from 1 to 6 ft; Boring location elevation and coordinates were estimated from the google earth;

4-8-12-15

17-17-17-24

12-14-14-24

16-21-17-17

9-12-8-7

10-3-3-3

2-2-3-6

3-5-8-12

50%

42%

83%

79%

100%

83%

50%

100%

7.2

NP

NP

NP

0.0- 2.0

2.0- 4.0

4.0- 6.0

6.0- 8.0

8.0- 10.0

13.0- 15.0

18.0- 20.0

23.0- 25.0

17.58

10.00

5.00

0.00

-1.50

-6.00

-7.00

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

Rig Type

Rig No.

Drive Hammer

Casing Auger Size

Size of Core

Size of Bit OD

Hammer Energy Ratio

Auger Depth

WATER TABLE CAVE-IN TABLE

Elev (ft) Time

(hours)

7/26/24

13.0 0.5

7/25/24

H. GuzmanA. Melorie

16.0 2.0

LB

IN

IN

IN

FT

Truck Mounted

CME55 Truck

3.25

Date

Inspector

Depth Below Surface

5.0

Depth Below Surface

At Drilling 7/26/24

Driller

9.8 0.5

A. Melorie

7/26/24

7/26/24

Date Started Date Completed

Logged by

Depth (ft)Elev (ft) DateTime

(hours)Depth (ft)

8.2

2of

NMC (%)

Sheet 1 of

REC (%)

M A

T L

Northing

Boring

SPT- Standard Penetration Test

1330304.078 454676.386

T-206, T-207

PM0003A21

SB-1

Contract No.

Geotech Consultant/ContractorConsultant

REC - RecoveryPI - Plasticity Index

LL - Liquid Limit

Legend: NMC - Natural Moisture Content

RQD - Rock Quality Designation Elev - Elevation

MATL- Material Graphics

Geotech - Geotechnical OD - Outside Diameter

BLOWS/

RQD

SAMPLE

NO.

Easting

REMARKSSAMPLE

DEPTH LL (%)

SPT SPOON/ROCK CORE

PI (%)

Boring and Sampling Conforms to ASTM/AASHTO:

LAB. INDEX TESTSDEPTH

IN

FEET

MATERIAL DESCRIPTION

ELEV.

IN

FEET

TSG/GEO/01

8-31-2015

CDM Smith

Project Description

Boring No. Station Ground Surface Elevation

WASHINGTON SUBURBAN SANITARY COMMISSION

STANDARD BORING LOG

WSSC Anacostia WWPS Surge Tanks Removal

CDM Smith/DMY EC

18.0 ft, '

W S

S C

S T

A N

D A

R D

B O

R

IN

G L

O G

[L E

T T

E R

S

IZ

E

W S

S C

_T E

M P

LA

T

E .G

D T

D

R A

F T

L O

G S

.7 .2

7.

4.

G P

J

/1

2/

0.3

5.0

8.0

13.0

19.0

20.0

3-in Topsoil

Moist, Brown, Medium Dense to Dense, Fine To Coarse, SILTY CLAYEY

SAND WITH GRAVEL

(SC-SM), (FILL)

Same, Mottled

Moist, Dark Gray, Loose To Dense, Fine To Coarse, CLAYEY SAND (SC), (COASTAL DEPOSIT)

Same, Gray and Brown

Moist, Mottled, Medium Dense, POORLY GRADED SAND WITH SILT and

GRAVEL(SP-SM),

(COASTAL DEPOSIT)

Wet, Mottled, Loose To Medium Dense, Fine To Coarse, POORLY GRADED

SAND WITH GRAVEL

(SP), Contains Trace Clay, (COASTAL DEPOSIT)

Wet, Gray, Medium Dense, Fine To Coarse CLAYEY

SAND (SC), (COASTAL

DEPOSIT)

BOTTOM OF HOLE

(TERMINATED)

Bulk sample was collected from 1 to 6 ft; Boring location elevation and coordinates were estimated from the google earth;

7-10-13-10

12-14-12-16

11-14-16-11

4-3-3-9

11-8-8-8

4-4-4-3

6-6-8-8

83%

100%

83%

50%

38%

58%

75%

11.2

11.8

19 NP

0.0- 2.0

2.0- 4.0

4.0- 6.0

6.0- 8.0

8.0- 10.0

13.0- 15.0

18.0- 20.0

16.75

12.00

9.00

4.00

-2.00

-3.00

S-1

S-2

S-3

S-4

S-5

S-6

S-7

Rig Type

Rig No.

Drive Hammer

Casing Auger Size

Size of Core

Size of Bit OD

Hammer Energy Ratio

Auger Depth

WATER TABLE CAVE-IN TABLE

Elev (ft) Time

(hours)

7/26/24

13.0 0.5

7/26/24

H. GuzmanA. Melorie

9.0 8.0

LB

IN

IN

IN

FT

Truck Mounted

CME45C Truck

3.25

Date

Inspector

Depth Below Surface

4.0

Depth Below Surface

At Drilling 7/26/24

Driller

8.6 0.5

A. Melorie

7/26/24

7/26/24

Date Started Date Completed

Logged by

Depth (ft)Elev (ft) DateTime

(hours)Depth (ft)

8.4

2of

NMC (%)

Sheet 1 of

REC (%)

M A

T L

Northing

Boring

SPT- Standard Penetration Test

1330302.115 454635.959

T-206, T-207

PM0003A21

SB-2

Contract No.

Geotech Consultant/ContractorConsultant

REC - RecoveryPI - Plasticity Index

LL - Liquid Limit

Legend: NMC - Natural Moisture Content

RQD - Rock Quality Designation Elev - Elevation

MATL- Material Graphics

Geotech - Geotechnical OD - Outside Diameter

BLOWS/

RQD

SAMPLE

NO.

Easting

REMARKSSAMPLE

DEPTH LL (%)

SPT SPOON/ROCK CORE

PI (%)

Boring and Sampling Conforms to ASTM/AASHTO:

LAB. INDEX TESTSDEPTH

IN

FEET

MATERIAL DESCRIPTION

ELEV.

IN

FEET

TSG/GEO/01

8-31-2015

CDM Smith

Project Description

Boring No. Station Ground Surface Elevation

WASHINGTON SUBURBAN SANITARY COMMISSION

STANDARD BORING LOG

WSSC Anacostia WWPS Surge Tanks Removal

CDM Smith/DMY EC

17.0 ft, '

W S

S C

S T

A N

D A

R D

B O

R

IN

G L

O G

[L E

T T

E R

S

IZ

E

W S

S C

_T E

M P

LA

T

E .G

D T

D

R A

F T

L O

G S

.7 .2

7.

4.

G P

J

/1

2/

APPENDIX C LABORATORY TESTING

Jay Kay Testing Project Number: 03.06675.01

Location: Prince George's County, MD

Sample Date: Summary of Laboratory Testing

Sample Identification Depth Atterberg Limits Compaction

SB-1 Bulk 1 6 5.1 - 21 18 3 - 133.9 7.8 A-2-4 - 18.4 SM

SB-1 S-5 8 10 7.2 - 18 NP NP - - - A-1-b - 10.3 SP-SM

SB-1 S-7A 18 19.5 15.0 - NP NP NP - - - A-3 - 3.6 SP

SB-2 Bulk 1 6 6.2 - 23 16 7 - 137.8 6.6 A-2-4 - 18.4 SC-SM

SB-2 S-5 8 10 11.2 - 19 NP NP - - - A-1-b - 7.2 SP-SM

SB-2 S-6 13 15 11.8 - - - - - - - - - 4.3 SP

B tt o m ft

(814) 404-9283 www.jaykaytesting.com

F in

U

C

S C la s s if ic a ti o n

A S

T M

D -2

A

A S

H T

O C la s s if ic a ti o n

M -1 e c if ic

G ra v it y

A S

T M

D -8 u id

L im it

A

S T

M D

-4

P la s ti c L im it

A

S T

M D

-4

M C

A

S T

M D

-2 rg a n ic

M a tt e r, A S

T M

D -2

08/05/24

B ri n g

I m p le

I

T p ft

Tested by: ST/JT Reviewed by: AM Jay Kay Testing

P la s ti c it y I n d e x

A

S T

M D

-4

M x im u m

D ry

D e n s it y lb

/f t³ ti m u m

M o is tu re

C o n te n t, .0 m m

Jay Kay Testing Project Number: 03.06675.01

Location: Prince George's County, MD

Sample Date: Summary of Atterberg Limit Testing

Atterberg Limit Results

Boring ID Sample ID Boring ID Sample ID

= SB-1 Bulk 1 6 21 18 3

SB-1 S-5 8 10 18 NP NP

SB-1 S-7A 18 19.5 NP NP NP

SB-2 Bulk 1 6 23 16 7

SB-2 S-5 8 10 19 NP NP

Tested by: ST/JT Reviewed by: AM

WSSC Anacostia WWPS Surge Tanks Removal

(814) 404-9283 www.jaykaytesting.com

Btm LL PL PI

Jay Kay Testing 08/05/24

Top Btm LL PL PI Top

ML

CL

MH or OH

CL-ML

ASTM D-4318

0 20 40 60 80 100 120 140

P la s ti c it y I n d e x

P I)

Liquid Limit,% (LL)

Project Number: 03.06675.01 Jay Kay Testing

Boring ID Sample ID Top Btm Location: Prince George's County, MD

SB-1 Bulk 1' 6' Sample Date:

Sieve Size Pass, %

- mm %

6"

3"

2"

1.5"

1"

3/4"

1/2"

3/8"

#4

#10

#20

#40

#60

#100

#200

% Gravel (> 4.75 mm) % Sand D10 -

Coarse Fine Coarse Medium Fine D30 - CC

5.5 19.6 = 25.1 8.5 15.8 32.2 = 56.5 D60 - CU

Liquid Limit, %

Plastic Limit, %

Plasticity Index, %

USCS (D-2487) AASHTO (M-145)

SM A-2-4

Soil Description (D-2487)

NMC Sample Type* Data 4

OM Data 2 Data 5

______________ Data 3 Data 6

+ 3/8"

08/05/24 Tested by: ST/JT Reviewed by: AM Jay Kay Testing

15.5%

Dark brown silty SAND with gravel

5.1% - -

0.147 26.0

0.074 18.4

Total Total -

0.85 60.7

0.42 50.6

0.25 35.7

9.51 84.5

4.75 74.9

2.00 66.4

25.4 96.6

19.0 94.5

12.7 89.2

75.0 -

50.8 -

37.5 100.0

ASTM D-6913

GRAVEL

Diameter

SAND

U.S. Standard Sieve

CLAY/SILT

Hydrometer

150.0 -

3" 3/4" 3/8" #4 #10 #40 #200 0.002

0.0010.010.1110100

P e rc e n t

F in e r

Particle Size, mm

ML

CL MH or OHCL-ML

A-Line: 0.73

PI: 3

Plasticity: SILT

ASTM D-4318

0 20 40 60 80 100 120 140

P la s ti c it y I n d e x

P

Liquid Limit, % (LL)

Boring ID Sample ID Top Btm Location: Prince George's County, MD

SB-1 S-5 8' 10' Sample Date:

Sieve Size Pass, %

- mm %

6"

3"

2"

1.5"

1"

3/4"

1/2"

3/8"

#4

#10

#20

#40

#60

#100

#200

% Gravel (> 4.75 mm) % Sand D10 0.0711

Coarse Fine Coarse Medium Fine D30 0.3214 CC

0.0 31.0 = 31.0 10.1 21.5 27.1 = 58.7 D60 2.2053 CU

Liquid Limit, %

Plastic Limit, %

Plasticity Index, %

USCS (D-2487) AASHTO (M-145)

SP-SM A-1-b

Soil Description (D-2487)

NMC Sample Type* Data 4

OM Data 2 Data 5

______________ Data 3 Data 6

+ 3/8"

08/05/24 Tested by: ST/JT Reviewed by: AM Jay Kay Testing

18.8%

NP

Dark brown poorly-graded SAND with silt and gravel

7.2% - -

Total Total 0.658

31.00

NP

0.25 23.1

0.147 15.5

0.074 10.3

2.00 58.9

0.85 51.2

0.42 37.4

12.7 85.6

9.51 81.2

4.75 69.0

37.5 -

25.4 -

19.0 100.0

150.0 -

75.0 -

50.8 -

ASTM D-6913

GRAVEL

Diameter

SAND

U.S. Standard Sieve

CLAY/SILT

Hydrometer

D10

D30

D60

Extrapolated diameter at

10% Passing: 0.07113

3" 3/4" 3/8" #4 #10 #40 #200 0.002

0.0010.010.1110100

P e rc e n t

F in e r

Particle Size, mm

ML

CL MH or OHCL-ML

A-Line: NP

PI: NP

Plasticity: SILT

ASTM D-4318

0 20 40 60 80 100 120 140

P la s ti c it y I n d e x

P

Boring ID Sample ID Top Btm Location: Prince George's County, MD

SB-1 S-7A 18' 19.5' Sample Date:

Sieve Size Pass, %

- mm %

6"

3"

2"

1.5"

1"

3/4"

1/2"

3/8"

#4

#10

#20

#40

#60

#100

#200

% Gravel (> 4.75 mm) % Sand D10 0.2070

Coarse Fine Coarse Medium Fine D30 0.3053 CC

6.7 12.5 = 19.2 5.1 22.8 49.3 = 77.2 D60 0.5100 CU

Liquid Limit, %

Plastic Limit, %

Plasticity Index, %

USCS (D-2487) AASHTO (M-145)

SP A-3

Soil Description (D-2487)

NMC Sample Type* Data 4

OM Data 2 Data 5

______________ Data 3 Data 6

+ 3/8"

08/05/24 Tested by: ST/JT Reviewed by: AM Jay Kay Testing

16.2%

NP

Brown poorly-graded SAND with gravel

15.0% - -

Total Total 0.883

2.46

NP

NP

0.25 15.6

0.147 5.5

0.074 3.6

2.00 75.7

0.85 69.6

0.42 52.9

12.7 86.1

9.51 83.8

4.75 80.8

37.5 -

25.4 100.0

19.0 93.3

150.0 -

75.0 -

50.8 -

ASTM D-6913

GRAVEL

Diameter

SAND

U.S. Standard Sieve

CLAY/SILT

Hydrometer

D10

D30

D60

3" 3/4" 3/8" #4 #10 #40 #200 0.002

0.0010.010.1110100

P e rc e n t

F in e r

Particle Size, mm

ML

CL MH or OHCL-ML

A-Line: NP

PI: NP

Plasticity: SILT

ASTM D-4318

NP/NP/NP

0 20 40 60 80 100 120 140

P la s ti c it y I n d e x

P

Boring ID Sample ID Top Btm Location: Prince George's County, MD

SB-2 Bulk 1' 6' Sample Date:

Sieve Size Pass, %

- mm %

6"

3"

2"

1.5"

1"

3/4"

1/2"

3/8"

#4

#10

#20

#40

#60

#100

#200

% Gravel (> 4.75 mm) % Sand D10 -

Coarse Fine Coarse Medium Fine D30 - CC

5.1 23.3 = 28.4 10.1 17.7 25.4 = 53.2 D60 - CU

Liquid Limit, %

Plastic Limit, %

Plasticity Index, %

USCS (D-2487) AASHTO (M-145)

SC-SM A-2-4

Soil Description (D-2487)

NMC Sample Type* Data 4

OM Data 2 Data 5

______________ Data 3 Data 6

+ 3/8"

08/05/24 Tested by: ST/JT Reviewed by: AM Jay Kay Testing

17.2%

Dark brown silty clayey SAND with gravel

6.2% - -

Total Total -

0.25 31.5

0.147 24.1

0.074 18.4

2.00 61.5

0.85 55.2

0.42 43.8

12.7 88.0

9.51 82.8

4.75 71.6

37.5 99.3

25.4 97.6

19.0 94.9

150.0 -

75.0 -

50.8 100.0

ASTM D-6913

GRAVEL

Diameter

SAND

U.S. Standard Sieve

CLAY/SILT

Hydrometer

3" 3/4" 3/8" #4 #10 #40 #200 0.002

0.0010.010.1110100

P e rc e n t

F in e r

Particle Size, mm

ML

CL MH or OHCL-ML

A-Line: 2.19

PI: 7

Plasticity: SILTY CLAY

ASTM D-4318

0 20 40 60 80 100 120 140

P la s ti c it y I n d e x

P

Boring ID Sample ID Top Btm Location: Prince George's County, MD

SB-2 S-5 8' 10' Sample Date:

Sieve Size Pass, %

- mm %

6"

3"

2"

1.5"

1"

3/4"

1/2"

3/8"

#4

#10

#20

#40

#60

#100

#200

% Gravel (> 4.75 mm) % Sand D10 0.1468

Coarse Fine Coarse Medium Fine D30 0.4930 CC

0.0 29.4 = 29.4 13.1 32.1 18.2 = 63.4 D60 2.3548 CU

Liquid Limit, %

Plastic Limit, %

Plasticity Index, %

USCS (D-2487) AASHTO (M-145)

SP-SM A-1-b

Soil Description (D-2487)

NMC Sample Type* Data 4

OM Data 2 Data 5

______________ Data 3 Data 6

+ 3/8"

08/05/24 Tested by: ST/JT Reviewed by: AM Jay Kay Testing

19.4%

NP

Dark brown poorly-graded SAND with silt and gravel

11.2% - -

Total Total 0.703

16.04

NP

0.25 13.8

0.147 10.0

0.074 7.2

2.00 57.5

0.85 44.2

0.42 25.4

12.7 86.0

9.51 80.6

4.75 70.6

37.5 -

25.4 -

19.0 100.0

150.0 -

75.0 -

50.8 -

ASTM D-6913

GRAVEL

Diameter

SAND

U.S. Standard Sieve

CLAY/SILT

Hydrometer

D10

D30

D60

3" 3/4" 3/8" #4 #10 #40 #200 0.002

0.0010.010.1110100

P e rc e n t

F in e r

Particle Size, mm

ML

CL MH or OHCL-ML

A-Line: NP

PI: NP

Plasticity: SILT

ASTM D-4318

0 20 40 60 80 100 120 140

P la s ti c it y I n d e x

P

Boring ID Sample ID Top Btm Location: Prince George's County, MD

SB-2 S-6 13' 15' Sample Date:

Sieve Size Pass, %

- mm %

6"

3"

2"

1.5"

1"

3/4"

1/2"

3/8"

#4

#10

#20

#40

#60

#100

#200

% Gravel (> 4.75 mm) % Sand D10 0.3000

Coarse Fine Coarse Medium Fine D30 0.7300 CC

0.0 42.4 = 42.4 12.8 28.6 11.9 = 53.3 D60 5.2950 CU

Liquid Limit, %

Plastic Limit, %

Plasticity Index, %

USCS (D-2487) AASHTO (M-145)

SP -

Soil Description (D-2487)

NMC Sample Type* Data 4

OM Data 2 Data 5

______________ Data 3 Data 6

+ 3/8"

08/05/24 Tested by: ST/JT Reviewed by: AM Jay Kay Testing

27.3%

Light brown poorly-graded SAND with gravel

11.8% - -

Total Total 0.335

17.65

0.25 8.0

0.147 5.6

0.074 4.3

2.00 44.8

0.85 33.2

0.42 16.2

12.7 83.1

9.51 72.7

4.75 57.6

37.5 -

25.4 -

19.0 100.0

150.0 -

75.0 -

50.8 -

ASTM D-6913

GRAVEL

Diameter

SAND

U.S. Standard Sieve

CLAY/SILT

Hydrometer

D10

D30

D60

3" 3/4" 3/8" #4 #10 #40 #200 0.002

0.0010.010.1110100

P e rc e n t

F in e r

Particle Size, mm

ML

CL MH or OHCL-ML

A-Line: -

PI: -

Plasticity: -

ASTM D-4318

0 20 40 60 80 100 120 140

P la s ti c it y I n d e x

P

Boring ID Sample ID Top Btm Location: Prince George's County, MD

SB-1 Bulk 1' 6' Sample Date:

Moisture-Density Relationship of Soils

STANDARD PROCTOR Uncorrected Corrected* Maximum Optimum

Test Method: ASTM D-698 (B) Maximum dry unit weight, lb/ft³ 129.8 133.9 Dry Unit Weight Water Content

Percent oversize particles: 15.5% Optimum water content 8.9% 7.8% 133.9 7.8%

Oversized particles sieve: 3/8-in. _____________________________________________________________ lb/ft³ (PCF)

Threshold for correction: >= 5.0% *Corrected for 15.5% oversized particles retained on the 3/8-in. sieve.

Zero Air Voids (100% Saturation)

Zero air voids curves: 2.65, 2.75, 2.85 Bulk Specific Gravity (assumed): 2.60

NMC LL PL PI % Fines USCS AASHTO Soil Description (D-2487)

5.1% 21% 18% 3% 18.4 SM A-2-4 Dark brown silty SAND with gravel

08/05/24 Tested by: ST/JT Reviewed by: AM Jay Kay Testing

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

D R

Y U

N

IT

W E

IG

H

T

L B

/F T

³ (P

C F

WATER CONTENT, %

Boring ID Sample ID Top Btm Location: Prince George's County, MD

SB-2 Bulk 1' 6' Sample Date:

Moisture-Density Relationship of Soils

STANDARD PROCTOR Uncorrected Corrected* Maximum Optimum

Test Method: ASTM D-698 (B) Maximum dry unit weight, lb/ft³ 133.6 137.8 Dry Unit Weight Water Content

Percent oversize particles: 17.2% Optimum water content 7.6% 6.6% 137.8 6.6%

Oversized particles sieve: 3/8-in. _____________________________________________________________ lb/ft³ (PCF)

Threshold for correction: >= 5.0% *Corrected for 17.2% oversized particles retained on the 3/8-in. sieve.

Zero Air Voids (100% Saturation)

Zero air voids curves: 2.65, 2.75, 2.85 Bulk Specific Gravity (assumed): 2.60

NMC LL PL PI % Fines USCS AASHTO Soil Description (D-2487)

6.2% 23% 16% 7% 18.4 SC-SM A-2-4 Dark brown silty clayey SAND with gravel

08/05/24 Tested by: ST/JT Reviewed by: AM Jay Kay Testing

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

D R

Y U

N

IT

W E

IG

H

T

L B

/F T

³ (P

C F

WATER CONTENT, %