C-05_Attachment_F_-_Dyke_Marsh_Draft_Construction_Specifications.pdf

US Army Corps of Engineers Baltimore District

DRAFT CONSTRUCTION

SPECIFICATIONS

DYKE MARSH RESTORATION

FAIRFAX COUNTY, VIRGINIA

JULY 2017

Dyke Marsh Restoration DYKMAR

PROJECT TABLE OF CONTENTS

DIVISION 01 - GENERAL REQUIREMENTS

01 00 00 ADMINISTRATIVE REQUIREMENTS

01 05 00 JOB CONDITIONS

01 22 00.00 10 PRICE AND PAYMENT PROCEDURES

01 32 01.00 10 PROJECT SCHEDULE

01 33 00 SUBMITTAL PROCEDURES

01 35 26 GOVERNMENTAL SAFETY REQUIREMENTS

01 42 00 SOURCES FOR REFERENCE PUBLICATIONS

01 45 00.00 10 QUALITY CONTROL

01 45 00.15 10 RESIDENT MANAGEMENT SYSTEM CONTRACTOR MODE(RMS CM)

01 50 00 TEMPORARY CONSTRUCTION FACILITIES AND CONTROLS

01 57 20.00 10 ENVIRONMENTAL PROTECTION

01 78 00 CLOSEOUT SUBMITTALS

DIVISION 02 - EXISTING CONDITIONS

02 93 61 LANDSCAPING FOR TIDAL FRESH WATER MARSH

DIVISION 31 - EARTHWORK

31 05 19 GEOTEXTILE

DIVISION 35 - WATERWAY AND MARINE CONSTRUCTION

35 31 19 STONEWORK

35 31 20 POLYMERIC MARINE MATTRESS

-- End of Project Table of Contents --

PROJECT TABLE OF CONTENTS Page 1

SECTION 01 00 00

ADMINISTRATIVE REQUIREMENTS

PART 1 GENERAL

1.1 SUBMITTALS

Government approval is required for submittals with a "G" designation;

submittals not having a "G" designation are for information only. When used, a designation following the "G" designation identifies the office that will review the submittal for the Government. The following shall be submitted in accordance with Section 01 33 00 SUBMITTAL PROCEDURES:

SD-01 Preconstruction Submittals

Photographs

Electronic photographs showing construction progress.

SD-03 Product Data

Cost or Pricing Data

Proof of actual equipment costs.

SD-05 Design Data

Progress Schedule; G RO.

A schedule that shows the manner in which the Contractor intends to prosecute the work.

1.2 PROGRESS SCHEDULING AND REPORTING (DEC 1998)

1.2.1 Practicable Progress Schedule

The Contractor shall submit for approval a practicable progress schedule in accordance with specification Section 01 32 01.00 10 PROJECT SCHEDULE showing the manner in which he intends to prosecute the work.

1.2.2 Software Package

The Contractor shall utilize an industry recognized QCS-W compatible scheduling software package to implement the requirements of Section 01 32

01.00 10 PROJECT SCHEDULE. The program and data must be Primavera-compatible in a Windows environment. These requirements are not intended to restrict the Contractors selection of an automated scheduling system but to establish a format which will allow use of the same program with government computers and automated information systems. The Contractor will provide at least one program installation and maintenance on government hardware complete with all program and data files. Such installation shall be maintained for the duration of the project until

SECTION 01 00 00 Page 1 fiscal completion and shall allow analysis and of the project schedule by government personnel or agents. The Contractor will be required to submit a submittal register, transmittal log and schedule that is compatible with the Corps of Engineers Quality Control System for Windows (QCS-W). The submittal register can be made available by the Corps of Engineers.

1.3 PAYMENTS TO CONTRACTORS: (NOV 1976)

For payment purposes only, an allowance will be made by the Contracting Officer of 100 percent of the invoiced cost of materials or equipment delivered to the site but not incorporated into the construction, pursuant to the Contract Clause entitled "PAYMENTS UNDER FIXED-PRICE CONSTRUCTION CONTRACTS". In order to be eligible for payment, the Contractor must provide satisfactory evidence that he has acquired title to such material or equipment, and that it will be utilized on the work covered by this contract. Further, all items must be properly stored and protected.

Earnings will be computed using 100% of invoiced value. (CENAB-CO-E)

1.4 PURCHASE ORDER: (SEP 1975)

One readable copy of all purchase orders for material and equipment, showing firm names and addresses, and all shipping bills, or memoranda of shipment received regarding such material and equipment, shall be furnished the appointed Contracting Officer's Representative as soon as issued. Such orders, shipping bills or memoranda shall be so worded or marked that all material and each item, piece or member of equipment can be definitely identified on the drawings. Where a priority rating is assigned to a contract, this rating, the required delivery date, and the scheduled shipping date shall also be shown on the purchase order. At the option of the Contractor, the copy of the purchase order may or may not indicate the purchase price. (CENAB-CO-E)

1.5 EQUIPMENT OWNERSHIP AND OPERATING EXPENSE SCHEDULE

IAW FAR 31.105(d)(2)(i)(b), equipment ownership and operating costs shall be determined using EP 1110-1-8, Construction Equipment Ownership and Operating Expense Schedule, Region II ( ht t p: / / www. publ i cat i ons. usace. ar my. mi l / Por t al s/ 76/ Publ i cat i ons/ Engi neer Pamphl et s/ EP_1110- 1- 8_Vol _02. pdf ?ver =2017- 05- 15- 125301- 463) .

1.6 PROJECT MEETINGS

Unless otherwise stated by the Contracting Officer (C)), project meetings shall be held at Fort Belvoir, VA, at a location specified by the Government.

1.7 NEGOTIATED MODIFICATIONS: (OCT 84)

Whenever profit is negotiated as an element of price for any modification to this contract with either prime or subcontractor, a reasonable profit shall be negotiated or determined by using the OCE Weighted Guidelines method outlined in EFARS 15.902. (Sugg. NAB 84-232)

1.8 PHOTOGRAPHS

Provide monthly, and within one month of the completion of work, above-water digital photographs in JPEG file format showing the sequence and progress of work. Take a minimum of ten digital photographs prior to the seventh day of each month of views and points located by the

SECTION 01 00 00 Page 2

Contracting Officer. Submit a view location sketch indicating points of view. Submit with the monthly invoice two sets of digital photographs each set on a separate CD-R, cumulative of all photos to date. Photographs for each month shall be in a separate monthly directory and each file shall be named to indicate its location on the view location sketch. The view location sketch shall also be provided on the CD as digital file.

All file names shall include a date designator. (CENAB-EN)

1.9 PARTNERING: (NOV 92)

In order to most effectively accomplish this contract, the Government is willing to form a cohesive partnership with the Contractor and its subcontractors. This partnership would strive to draw on the strengths of each organization in an effort to achieve a quality project done right the first time, within budget and on schedule. This partnership would be bilateral in make-up and participation will be totally voluntary. Any cost associated with effectuating this partnership will be agreed to by both parties and will be shared equally with no change in contract price.

(CENAB-EN-DT)

1.10 PERMITS

The permits listed below have been obtained by the Government or are in the approval process and may require additional action by the Contractor to become complete. After final approvals by the respective state agencies are received, the Government will furnish approval letters and permits to the Contracting Officer who will furnish the Contractor all such permits before or during construction. The Contractor shall abide by all permit requirements.

a. PERMIT DATA WILL BE ADDED AT A LATER SUBMISSION

1.11 MEASUREMENT AND PAYMENT

No separate measurement and payment will be made for the work performed in this Section 01 00 00, ADMINISTRATIVE REQUIREMENTS, specified herein; and all costs in connection therewith shall be considered a subsidiary obligation of the Contractor, and shall be included in the overall cost of the work.(CENAB)

PART 2 PRODUCTS

NOT APPLICABLE

PART 3 EXECUTION

NOT APPLICABLE

ATTACHMENTS:

-- End of Section --

SECTION 01 00 00 Page 3

SECTION 01 05 00

JOB CONDITIONS

PART 1 GENERAL

1.1 LAYOUT OF WORK: (APR 1965 OCE)

The Contractor shall lay out his work and shall be held responsible for all measurements in connection therewith. The Contractor shall furnish, at his own expense, all such platforms, barges, equipment, tools and material and all labor as may be required in laying out any part of the work. It shall be the responsibility of the Contractor to maintain and preserve all control points and markers established by him during the duration of construction . GPS benchmark positioning is recommended.

1.2 PHYSICAL DATA: (APR 1984)

Data and information furnished or referred to below is for the Contractor's information. The Government shall not be responsible for any interpretation or conclusion drawn from the data or information by the Contractor. (CENAB)

1.2.1 Transportation Facilities

Dyke Marsh is located in Virginia off the east side of George Washington Parkway about 1-1/2 miles south of I-495 (Alexandria). Other than the Mt.

Vernon bike/walking trail and a nature path, there is no pedestrian or construction access to the marsh, so all construction access shall be from the Potomac River. The Contractor shall make its own investigation and determinations as to the availability and adequacy of the transportation for his use for construction purposes. No transportation will be provided by USACE or the National Park Service.

1.2.2 Explorations

The physical conditions indicated on the drawings and in the specifications are the result of site investigations by surveys, borings, and other in-situ testing methods including flat plate dilatometer tests (DMT). Measured and interpreted parameters obtained from the DMT in-situ test is included in the Final Geotechnical Report. Foundation exploration logs and the Geotechnical Report are included at the end of this Section.

The explorations logs and DMT results presented represent the best subsurface information available; however, variations may exist in the subsurface between samples and between boring and DMT locations and will vary with time and season. The Subsurface samples from the investigation are available for inspection by contacting the Point of Contact listed for inquiries in the Solicitation. Bidders shall allow 7 business days for access to the samples to be arranged. Portions of the geotechnical report other than the boring logs, in-situ testing results (measured parameters only), and laboratory testing data are interpretive, are provided as background information only, and shall not be used as a basis for bid or construction.

SECTION 01 05 00 Page 1

1.3 UTILITIES

1.3.1 Availability of Utilities Including Lavatory Facilities: (JUN 1980)

It shall be the responsibility of the Contractor to provide all land or construction plant utilities he may require during the entire life of the contract. He shall make his own investigation and determinations as to the availability and adequacy of utilities for his use for construction purposes and domestic consumption. For land-based utilities, he shall install and maintain all necessary supply lines, connections, piping, and meters if required, but only at such locations and in such manner as approved by the Contracting Officer. Before final acceptance of work under this contract, all temporary supply lines, connections and piping installed by the Contractor shall be removed by him in a manner satisfactory to the Contracting Officer. (CENAB)

1.4 DISPOSAL OF EXISTING MATERIAL AND EQUIPMENT: (DEC 1975)

All removed, dismantled or demolished material not specified or indicated to be reinstalled under this contract or otherwise retained for disposal on Government land will become the property of the Contractor and shall be promptly removed from the site and disposed of by the Contractor at his own expense and responsibility. (CENAB)

1.5 COMPLIANCE WITH DYKE MARSH REGULATIONS: (JUL 1980)

The site of the work is at a Federal wildlife preserve and all rules and regulations issued by the National Park Service or Contracting Officer covering pollution control and wildlife preservation shall be observed by the Contractor. Information regarding these requirements may be obtained by contacting the Contracting Officer, who will provide such information or assist in obtaining same from appropriate authorities. (MEMO)

1.6 STREET USE RESTRICTIONS

There is no road access to the actual project site, and truck traffic is prohibited on George Washington Parkway.

1.7 MOORING OF VESSELS

Contact the United States Coast Guard (https://www.uscg.mil/) regarding necessary warning signage to mariners for extended mooring periods.

1.8 OBSTRUCTION OF RIVER

The Government will not undertake to keep the channel free from vessels or other obstructions, except to the extent of such regulations, if any, as may be prescribed by the Secretary of the Army, in accordance with the provisions of Section 7 of the River and Harbor Act approved 8 August 1917. The Contractor shall be required to conduct the work in such manner as to obstruct navigation as little as possible, and in case the Contractor's plant so obstructs the channel as to make difficult or endanger the passage of vessels, said plant shall be promptly moved on the approach of any vessels to such an extent as may be necessary to afford a safe practicable passage. Upon completion of the work the Contractor shall promptly remove his plant, including ranges, buoys, piles, and other marks placed by him under the contract in navigable waters or on shore.

SECTION 01 05 00 Page 2

1.9 TRANSPORTATION FOR GOVERNMENT PERSONNEL

The Contractor will be required to furnish, on the request of the Contracting Officer, any Government inspector, or authorized representative, suitable transportation from all points on shore designated by the Contracting Officer to and from the project area.

1.10 TIME EXTENSIONS FOR UNUSUALLY SEVERE WEATHER

1.10.1 Procedure for Determination

This provision specifies the procedure for determination of time extensions for unusually severe weather in accordance the contract clause entitled "Default: (Fixed Price Construction)". In order for the Contracting Officer to award a time extension under this clause, the following conditions must be satisfied:

a. The weather experienced at the project site during the contract period must be found to be unusually severe, that is, more severe than the adverse weather anticipated for the project location during any given month.

b. The unusually severe weather must actually cause a delay to the completion of the project. The delay must be beyond the control and without the fault or negligence of the contractor.

1.10.2 Anticipated Adverse Weather Delays

The following schedule of monthly anticipated adverse weather delays is based on National Oceanic and Atmospheric Administration (NOAA) or similar data for the project location and will constitute the base line for monthly weather time evaluations. The contractor's progress schedule must reflect these anticipated adverse weather delays in all weather dependent activities.

MONTHLY ANTICIPATED ADVERSE WEATHER DELAY

WORK DAYS BASED ON (5) DAY WORK WEEK

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

6 6 6 8 6 6 7 5 3 5 5 5

1.10.3 Impact

Upon acknowledgment of the Notice to Proceed (NTP) and continuing throughout the contract, the contractor will record on the daily CQC report, the occurrence of adverse weather and resultant impact to normally scheduled work. Actual adverse weather delay days must prevent work on critical activities for 50 percent or more of the contractor's scheduled work day. The number of actual adverse weather delay days shall include days impacted by actual adverse weather (even if adverse weather occurred in previous month), be calculated chronologically from the first to the last day of each month, and be recorded as full days. If the number of actual adverse weather delay days exceeds the number of days anticipated in paragraph "Anticipated Adverse Weather Delays", above, the Contracting Officer will convert any qualifying delays to calendar days, giving full consideration for equivalent fair weather work days, and issue a modification in accordance with the contract clause entitled "Default (Fixed Price Construction)".

SECTION 01 05 00 Page 3

1.11 WORKING HOURS

Working hours shall be as specified at the pre-proposal site visit.

1.12 LIMITS OF WORK AREAS

The limits of work areas as shown on the drawings are necessarily approximate. In case of doubt as to the actual limits of any work area, determination as to the actual limits will be made by the Contracting Officer.

1.13 DAMAGE TO WORK (1966 MAR OCE)

The responsibility for damage to any part of the permanent work shall be as set forth in the "Permits and Responsibilities" clause of the Contract Clauses. However, if, in the judgment of the Contracting Officer, any part of the permanent work performed by the Contractor is damaged by flood, earthquake, or hurricane which damage is not due to the failure of the Contractor to take reasonable precautions or to exercise sound engineering and construction practices in the conduct of the work, the Contractor will make the repairs as ordered by the Contracting Officer and full compensation for such repairs will be made at the applicable contract unit or lump sum prices as fixed and established in the contract. If, in the opinion of the Contracting Officer, there are no contract unit or lump sum prices applicable to any part of such work an equitable adjustment pursuant to the "Changes" clauses of the Contract Clauses, will be made as full compensation for the repairs of that part of the permanent work for which there are no applicable contract unit or lump sum prices. Except as herein provided, damage to all work (including temporary construction), utilities, materials, equipment and plant shall be repaired to the satisfaction of the Contracting Officer at the Contractor's expense, regardless of the cause of such damage. (CENAB)

1.14 ENVIRONMENTAL LITIGATION (1974 NOV OCE)

If the performance of all or any part of the work is suspended, delayed, or interrupted due to an order of a court of competent jurisdiction as a result of environmental litigation, as defined below, the Contracting Officer, at the request of the Contractor, shall determine whether the order is due in any part to the acts or omissions of the Contractor or a Subcontractor at any tier not required by the terms of this contract. If it is determined that the order is not due in any part to acts or omissions of the Contractor or a Subcontractor at any tier other than as required by the terms of this contract, such suspension, delay, or interruption shall be considered as if ordered by the Contracting Officer in the administration of this contract under the terms of the "Suspension of Work" clause of the Contract Clauses. The period of such suspension, delay or interruption shall be considered unreasonable, and an adjustment shall be made for any increase in the cost of performance of this contract (excluding profit) as provided in that clause, subject to all the provisions thereof.

The term "environmental litigation", as used herein, means a lawsuit alleging that the work will have an adverse effect on the environment or that the Government has not duly considered, either substantively or procedurally, the effect of the work on the environment. (CENAB)

SECTION 01 05 00 Page 4

1.15 MEASUREMENT AND PAYMENT

No separate measurement and payment will be made for the work performed in this Section 01 05 00, JOB CONDITIONS, specified herein; and all costs in connection therewith shall be considered a subsidiary obligation of the Contractor, and shall be included in the overall cost of the work.(CENAB)

PART 2 PRODUCTS

NOT APPLICABLE

PART 3 EXECUTION

NOT APPLICABLE

-- End of Section --

SECTION 01 05 00 Page 5

DYKE MARSH RESTORATION PROJECT

BELLE HAVEN, VIRGINIA

SUBSURFACE EXPLORATION NOTES

1. EXPLORATION WAS PERFORMED DURING OCTOBER 2015.

2. DRILL HOLES (DH) WERE ACCOMPLISHED BY STANDARD PENETRATION TEST

PROCEDURE (SPT, ASTM - 1586) USING A 1-3/8"ID SPLIT SPOON SAMPLER.

SAMPLE SPOONS WERE ADVANCED BY A 140# AUTOMATIC HAMMER FALLING 30".

THESE HOLES WERE POWER AUGERED BETWEEN SAMPLES UNLESS OTHERWISE

INDICATED. BLOW COUNTS SHOWN ARE FOR 0.5' OF DRIVE, UNLESS OTHERWISE

INDICATED.

ALL BORINGS WERE DRILLED BY A CME-45. RIG MOUNTED ON A BARGE IN THE

POTOMAC RIVER.

3. BLOW COUNTS REQUIRED TO ADVANCE SAMPLE SPOON ARE SHOWN IN COLUMN (a).

WOH - DENOTES WEIGHT OF HAMMER

WOR - DENOTES WEIGHT OF ROD

4. COLUMN (b) SHOWS THE NATURAL WATER CONTENTS IN PERCENT OF DRY WEIGHT

OF THOSE SAMPLES TESTED.

5. SOIL DESCRIPTIONS ARE SHOWN IN COLUMN (c).

6. SOIL DESCRIPTIONS ARE LABORATORY CLASSIFICATIONS BASED ON THE UNIFIED

SOIL CLASSIFICATION SYSTEM (ASTM D2487/2488), EXCEPT THOSE INDICATED

THUS (**), WHICH ARE FIELD INSPECTOR'S CLASSIFICATIONS.

7. NO GROUNDWATER READINGS WERE TAKEN SINCE EXPLORATION WAS LOCATED IN

THE POTOMAC RIVER.

NT - INDICATES GROUNDWATER READING NOT TAKEN

8. START OF BORING (0.0), REPRESENTS THE WATER SURFACE OF THE POTOMAC

RIVER AT TIME OF DRILLING.

9. DEPTH OF RIVER WATER SHOWN ON EACH BORING LOG WAS DETERMINED BY

SOUNDING WITH WEIGHTED TAPE MEASURE TO TOP OF SEDIMENT PRIOR TO

SAMPLING.

VERTICAL DATUM: M.L.L.W., FOR THE '60 TO '78 TIDAL EPOCH.

HORIZONTAL DATUM: NORTH AMERICAN 1983 DATUM, VIRGINIA STATE PLANE

COORDINATE SYSTEM.

10. FOR LOCATIONS OF SUBSURFACE EXPLORATIONS, SEE BORING LOCATION PLAN.

6.5

9.2

10.5

13.0

15.5

18.0

20.5

23.0

25.5

WOR -

WOR-WOR

WOH-WOH-WOH

WOH-WOH-WOH

1-WOR-WOR

WOR-1-6

3-1-3

1-4-7

78-50-57

7-14-12

10-18-24

33.6%

19.9%

NT

SPT

Water Jet

CA

Odex

WHILE DRILLING:

GROUNDWATER DATA

ON COMPLETION:

NT

Fill

Cored

Fish Tail Vibra Core

Hand

24 Hr. READING:

300 lb Tubex

DH-1

Auger

NT

DYKE MARSH

Depth(ft)

E

N

COMPLETED:

STA.

(d) (a) (b)

6962163

TOP ELEV:

(c)

DH-1

11897412

October 27, 2015

BELLE HAVEN, VA.OFFSET: 1 of 2

N A

B

F

IN

A L

G E

O T

E C

H L

O G

D Y

K E

M A

R S

H V

A

U G

.G P

J A

C E

M V

D W

IT

H

R A

P

ID

C P

T

9_

3_

.G

D T

/1

4/

Water

SILTY SAND, dark grayish brown, medium to fine grained, wet, soft, with rootlets, and wood.

SANDY LEAN CLAY (CL), brown, moist, soft, trace gravel.

SANDY LEAN CLAY (CL), dark gray, moist, trace rootlets.

SANDY LEAN CLAY (CL), brown, wet, soft, trace fine gravel.

SILTY SAND (SM), pinkish gray, medium to fine grained, wet, trace gravel.

SILTY SAND WITH GRAVEL (SM), grayish brown, wet.

very moist

WELL GRADED GRAVEL WITH SILT AND SAND (GW-GM), pale brown, fine to coarse grained, very moist.

SILTY GRAVEL WITH SAND (GM), grayish brown, fine to coarse grained, wet.

32.5

38.3

43.3

48.3

51.5

7-5-7

1-4-11

WOR-7-10

4-10-18

DYKE MARSH

Depth(ft)

E

N

COMPLETED:

STA.

(d) (a) (b)

6962163

TOP ELEV:

(c)

DH-1

11897412

October 27, 2015

BELLE HAVEN, VA.OFFSET: 2 of 2

N A

B

F

IN

A L

G E

O T

E C

H L

O G

D Y

K E

M A

R S

H V

A

U G

.G P

J A

C E

M V

D W

IT

H

R A

P

ID

C P

T

9_

3_

.G

D T

/1

4/

SILTY SAND WITH GRAVEL (SM), light yellowish brown, coarse to fine grained, wet.

CLAYEY SAND (SC), gray, fine to medium grained, very moist.

CLAYEY SAND (SC), light brownish gray, medium to fine grained, moist.

SILTY SAND (SM), gray, medium to fine grained, wet, trace gravel.

BOTTOM OF HOLE

Notes:

DH-1 sampling started at 730 and was compled at 1215. At the start of sampling the tide was 3.0 ft above mean low tide and at the end of sampling 0.5 ft above mean low tide. The GPS coordinates of the boring are 38 45' 26.6" N and 077 02' 47.0" W. Sampled using a standard 1 3/8" split spoon driven automatically by a 140 lbs hammer dropped 30".

13.5

15.5

18.0

23.0

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

85.9%

71.2%

NT

SPT

Water Jet

CA

Odex

WHILE DRILLING:

GROUNDWATER DATA

ON COMPLETION:

NT

Fill

Cored

Fish Tail Vibra Core

Hand

24 Hr. READING:

300 lb Tubex

DH-2

Auger

NT

DYKE MARSH

Depth(ft)

E

N

COMPLETED:

STA.

(d) (a) (b)

6962232

TOP ELEV:

(c)

DH-2

11897681

October 29, 2015

BELLE HAVEN, VA.OFFSET: 1 of 2

N A

B

F

IN

A L

G E

O T

E C

H L

O G

D Y

K E

M A

R S

H V

A

U G

.G P

J A

C E

M V

D W

IT

H

R A

P

ID

C P

T

9_

3_

.G

D T

/1

4/

Water

SILT WITH SAND (ML), dark grayish brown, wet, soft, and shell fragments.

LEAN TO FAT CLAY (CL), dark gray, wet, soft, with sand, and shell fragments.

ELASTIC SILT (MH), dark grayish brown, wet.

very moist

40.5

43.3

48.3

51.5

WOR-WOH

3-4-8

4-7-8

2-4-7

53.1%

DYKE MARSH

Depth(ft)

E

N

COMPLETED:

STA.

(d) (a) (b)

6962232

TOP ELEV:

(c)

DH-2

11897681

October 29, 2015

BELLE HAVEN, VA.OFFSET: 2 of 2

N A

B

F

IN

A L

G E

O T

E C

H L

O G

D Y

K E

M A

R S

H V

A

U G

.G P

J A

C E

M V

D W

IT

H

R A

P

ID

C P

T

9_

3_

.G

D T

/1

4/

ELASTIC SILT WITH SAND (MH), trace gravel.

CLAYEY SAND (SC), brownish yellow, medium to fine grained, moist, soft, trace gravel.

CLAYEY SAND (SC), light gray, medium to fine grained, very moist.

SILTY SAND (SM), light gray, medium to fine grained, very moist, medium stiff.

SANDY LEAN TO FAT CLAY (CL), light brownish gray, moist, medium stiff.

BOTTOM OF HOLE

Notes:

DH-2 sampling started at 900 and was compled at 1110. At the start of sampling the tide was 3.0 ft above mean low tide and at the end of sampling 2.0 ft above mean low tide. The GPS coordinates of the boring are 38 45' 27.3" N and 077 02' 43.6" W. Sampled using a standard 1 3/8" split spoon driven automatically by a 140 lbs hammer dropped 30".

DH-2 was plunked to 13.5 ft before drilling, however driller noted that the augers started turning up very soft material at 10.5 ft.

13.3

15.4

18.0

20.5

25.5

28.0

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR

92.9%

91.2%

NT

SPT

Water Jet

CA

Odex

WHILE DRILLING:

GROUNDWATER DATA

ON COMPLETION:

NT

Fill

Cored

Fish Tail Vibra Core

Hand

24 Hr. READING:

300 lb Tubex

DH-3

Auger

NT

DYKE MARSH

Depth(ft)

E

N

COMPLETED:

STA.

(d) (a) (b)

6962336

TOP ELEV:

(c)

DH-3

11897909

October 29, 2015

BELLE HAVEN, VA.OFFSET: 1 of 2

N A

B

F

IN

A L

G E

O T

E C

H L

O G

D Y

K E

M A

R S

H V

A

U G

.G P

J A

C E

M V

D W

IT

H

R A

P

ID

C P

T

9_

3_

.G

D T

/1

4/

Water

LEAN CLAY WITH SAND (CL), dark grayish brown, wet, soft, trace gravel, and shell fragments.

FAT CLAY WITH SAND (CH), dark grayish brown, wet, soft.

LEAN TO FAT CLAY (CL), with sand, and shell fragments.

FAT CLAY WITH SAND (CH), dark grayish brown, wet.

No Sample

POORLY GRADED SAND (SP), brown, coarse to fine grained, wet.

43.3

48.3

51.5

1-1-1

5-6-11

3-9-11

4-5-12

DYKE MARSH

Depth(ft)

E

N

COMPLETED:

STA.

(d) (a) (b)

6962336

TOP ELEV:

(c)

DH-3

11897909

October 29, 2015

BELLE HAVEN, VA.OFFSET: 2 of 2

N A

B

F

IN

A L

G E

O T

E C

H L

O G

D Y

K E

M A

R S

H V

A

U G

.G P

J A

C E

M V

D W

IT

H

R A

P

ID

C P

T

9_

3_

.G

D T

/1

4/

No Sample

CLAYEY SAND (SC), gray, medium to fine grained, moist.

SILTY SAND (SM), gray, medium to fine grained, wet.

SANDY FAT CLAY (CH), greenish gray, moist.

BOTTOM OF HOLE

Notes:

DH-3 sampling started at 1208 and was compled at 1415. At the start of sampling the tide was 2.0 ft above mean low tide and at the end of sampling 0.5 ft above mean low tide. The GPS coordinates of the boring are 38 45' 28.3" N and 077 02' 40.7" W. Sampled using a standard 1 3/8" split spoon driven automatically by a

9.5

11.0

13.0

18.0

20.5

27.1

28.0

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOH

WOR-WOR-WOR

WOR-WOH-1

WOR-WOH-WOH

118.7%

100.2%

86.2%

44.8%

NT

SPT

Water Jet

CA

Odex

WHILE DRILLING:

GROUNDWATER DATA

ON COMPLETION:

NT

Fill

Cored

Fish Tail Vibra Core

Hand

24 Hr. READING:

300 lb Tubex

DH-4

Auger

NT

DYKE MARSH

Depth(ft)

E

N

COMPLETED:

STA.

(d) (a) (b)

6962481

TOP ELEV:

(c)

DH-4

11898112

November 2, 2015

BELLE HAVEN, VA.OFFSET: 1 of 2

N A

B

F

IN

A L

G E

O T

E C

H L

O G

D Y

K E

M A

R S

H V

A

U G

.G P

J A

C E

M V

D W

IT

H

R A

P

ID

C P

T

9_

3_

.G

D T

/1

4/

Water

SILT WITH SAND (ML), dark gray, wet, plastic to very soft, trace shell fragments.

FAT CLAY WITH SAND (CH), dark gray, wet, very soft.

ELASTIC SILT WITH SAND (MH), dark gray, wet, very soft, trace shell fragments.

ELASTIC SILT WITH SAND (MH), dark grayish brown, very moist, very soft.

FAT CLAY WITH SAND (CH), dark grayish brown, very moist.

SILTY SAND (SM), brown, medium to fine grained, moist, very soft, trace wood.

SANDY LEAN CLAY (CL), grayish brown, medium to fine grained, wet.

36.8

41.8

50.0

WOR-WOH-WOH

WOH-1-1

5-4-5

4-5-6

DYKE MARSH

Depth(ft)

E

N

COMPLETED:

STA.

(d) (a) (b)

6962481

TOP ELEV:

(c)

DH-4

11898112

November 2, 2015

BELLE HAVEN, VA.OFFSET: 2 of 2

N A

B

F

IN

A L

G E

O T

E C

H L

O G

D Y

K E

M A

R S

H V

A

U G

.G P

J A

C E

M V

D W

IT

H

R A

P

ID

C P

T

9_

3_

.G

D T

/1

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SANDY LEAN CLAY (CL), grayish brown, medium to fine grained, wet. (continued from previous page)

SILTY SAND (SM), grayish brown, medium to fine grained, wet, very soft.

POORLY GRADED SAND WITH GRAVEL (SP), grayish brown, coarse to fine grained, wet.

BOTTOM OF HOLE

5.5

7.3

9.0

10.8

13.0

20.5

23.0

25.5

27.3

31.8

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOH

WOR-WOR-WOH

WOR-WOR-WOR

WOR-WOH-WOH

WOR-1-2

2-1-3

104.2%

81.3%

76.4%

NT

SPT

Water Jet

CA

Odex

WHILE DRILLING:

GROUNDWATER DATA

ON COMPLETION:

NT

Fill

Cored

Fish Tail Vibra Core

Hand

24 Hr. READING:

300 lb Tubex

DH-5

Auger

NT

DYKE MARSH

Depth(ft)

E

N

COMPLETED:

STA.

(d) (a) (b)

6962657

TOP ELEV:

(c)

DH-5

11898324

November 3, 2015

BELLE HAVEN, VA.OFFSET: 1 of 2

N A

B

F

IN

A L

G E

O T

E C

H L

O G

D Y

K E

M A

R S

H V

A

U G

.G P

J A

C E

M V

D W

IT

H

R A

P

ID

C P

T

9_

3_

.G

D T

/1

4/

Water

No Sample

LEAN CLAY WITH SAND (CL), gray, wet.

FAT CLAY WITH SAND (CH), dark grayish brown, wet, very soft.

LEAN TO FAT CLAY (CL), dark grayish brown, wet, with sand, trace wood.

ELASTIC SILT WITH SAND (MH), gray, wet, trace shell fragments.

FAT CLAY WITH SAND (CH), grayish brown, very moist.

FAT CLAY WITH SAND (CH), gray, very moist, trace shell fragments.

CLAYEY SAND WITH GRAVEL (SC), gray, medium to fine grained, wet.

SILTY SAND (SM), grayish brown, medium to fine grained, wet, trace gravel.

50.0

WOH-WOH-1

1-2-3

4-4-4

4-4-5

DYKE MARSH

Depth(ft)

E

N

COMPLETED:

STA.

(d) (a) (b)

6962657

TOP ELEV:

(c)

DH-5

11898324

November 3, 2015

BELLE HAVEN, VA.OFFSET: 2 of 2

N A

B

F

IN

A L

G E

O T

E C

H L

O G

D Y

K E

M A

R S

H V

A

U G

.G P

J A

C E

M V

D W

IT

H

R A

P

ID

C P

T

9_

3_

.G

D T

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4/

POORLY GRADED SAND (SP), light brownish gray, medium to fine grained, wet, trace wood. (continued from previous page)

POORLY GRADED SAND WITH SILT AND GRAVEL (SP-SM), grayish brown, medium to fine grained, wet.

POORLY GRADED SAND WITH GRAVEL (SP), light brown, coarse to fine grained, wet, very loose.

BOTTOM OF HOLE

Notes:

Test conducted from 0855AM to 1100AM

13.0

15.5

20.5

23.0

25.5

27.5

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-WOR-WOR

WOR-1-1

126.7%

NT

SPT

Water Jet

CA

Odex

WHILE DRILLING:

GROUNDWATER DATA

ON COMPLETION:

NT

Fill

Cored

Fish Tail Vibra Core

Hand

24 Hr. READING:

300 lb Tubex

DH-6

Auger

NT

DYKE MARSH

Depth(ft)

E

N

COMPLETED:

STA.

(d) (a) (b)

6962545

TOP ELEV:

(c)

DH-6

11897660

October 29, 2015

BELLE HAVEN, VA.OFFSET: 1 of 1

N A

B

F

IN

A L

G E

O T

E C

H L

O G

D Y

K E

M A

R S

H V

A

U G

.G P

J A

C E

M V

D W

IT

H

R A

P

ID

C P

T

9_

3_

.G

D T

/1

4/

Water

LEAN CLAY WITH SAND (CL), dark gray, very moist, soft.

LEAN TO FAT CLAY (CL), dark gray, wet, with fine sand, trace rootlets.

ELASTIC SILT WITH SAND (MH), dark grayish brown, wet, soft, trace shell fragments.

LEAN TO FAT CLAY (CL), grayish brown, wet, with sand.

FAT CLAY WITH SAND (CH), gray, very moist.

grayish brown

LEAN TO FAT CLAY (CL), grayish brown, very moist, with sand.

BOTTOM OF HOLE

Notes:

DH-3 sampling started at 1447 and was compled at 1615. At the start of sampling the tide was 0.5 ft above mean low tide and at the end of sampling 0.5 ft below mean low tide. The GPS coordinates of the boring are 38 45' 30.4" N and 077 02' 43.8" W. Sampled using a standard 1 3/8" split spoon driven automatically by a

13.0

15.5

18.0

21.3

26.8 27.5

WOR-WOR-WOR

WOH-WOH-WOH

WOR-WOR-WOR

WOR-WOR-WOR

WOH-WOH-WOH

WOH-WOH-1

WOR-1-1

NT

SPT

Water Jet

CA

Odex

WHILE DRILLING:

GROUNDWATER DATA

ON COMPLETION:

NT

Fill

Cored

Fish Tail Vibra Core

Hand

24 Hr. READING:

300 lb Tubex

DH-7

Auger

NT

DYKE MARSH

Depth(ft)

E

N

COMPLETED:

STA.

(d) (a) (b)

6972242

TOP ELEV:

(c)

DH-7

11904918

October 26, 2015

BELLE HAVEN, VA.OFFSET: 1 of 1

N A

B

F

IN

A L

G E

O T

E C

H L

O G

D Y

K E

M A

R S

H V

A

U G

.G P

J A

C E

M V

D W

IT

H

R A

P

ID

C P

T

9_

3_

.G

D T

/1

4/

Water

SANDY LEAN CLAY (CL), gray, wet, trace gravel.

No Sample

CLAYEY SAND (SC), gray, medium to fine grained, wet, soft, with shell fragments.

grayish brown

LEAN CLAY WITH SAND (CL), grayish brown, very moist.

SILTY SAND (SM), grayish brown, medium to fine grained, wet.

BOTTOM OF HOLE

Notes:

DH-7 sampling started at 1530 and was compled at 1715. At the start of sampling the tide was 0.5 ft above mean low tide and at the end of sampling 2.5 ft above mean low tide. The GPS coordinates of the boring are WGS 8438 47' 05.1" N and 077 01' 10.2" W. Sampled using a standard 1 3/8" split spoon driven automatically by a 140 lbs hammer dropped 30".

Prepared by:

U.S. Army Engineer District, Baltimore

Engineering Division Geotechnical Branch

July 2017

US Army Corps of Engineers Baltimore District July 2017

Dyke Marsh Restoration Project

Belle Haven, Virginia

Final Geotechnical Report

THIS GEOTECHNICAL REPORT IS

PROVIDED FOR INFORMATIONAL

PURPOSES ONLY AND IS NOT

INTENDED FOR USE AS A BASIS

FOR BID OR CONSTRUCTION

LIMITATIONS: Recommendations provided in this report are based upon data obtained from limited subsurface explorations. This report does not reflect conditions that may occur between locations investigated, or between sampling intervals within the test borings and flat plate dilatometers (DMT’s); and will vary with time and season. Soil Profiles contained in this report are based upon this offices interpretation only; actual conditions will vary. The opinions, recommendations, and conclusions expressed in this report are those of the Geotechnical Engineer and represent interpretations of the subsurface conditions, in-situ and laboratory testing, and the results of analyses and studies conducted for design. The report was prepared for design purposes only and is not intended for use as a basis for bid or construction.

TABLE OF CONTENTS

1. PROJECT LOCATION AND DESCRIPTION

2. GEOTECHNICAL SCOPE OF WORK

3. PREVIOUS 1976 INVESTIGATIONS

4. PHASE 1 SUBSURFACE INVESTIGATIONS

5. PHASE 2 SUBSURFACE INVESTIGATIONS

6. LABORATORY TESTING

7. REGIONAL GEOLOGY

8. SOIL STRATIGRAPHY

9. MUDLINE ELEVATION

10. ESTIMATED FAILURE DEPTH (MUDWAVE) OF FOUNDATION SOILS

11. ANTACIPATED SETTLEMENTS OF STONE BREAKWATER

12. GENERAL LIMITATIONS

13. POINT OF CONTACT

APPENDICIES

Appendix A

Location Map General Plan Subsurface Exploration Plan

Appendix B

Phase 1 Subsurface Investigations (October/November 2015)

Appendix C

Phase 2 Subsurface Investigations (May/August 2016)

Appendix D

Phase 1 and 2 Laboratory Test Results

Appendix E

Selected pages from Technical Report D-76-6 FEASIBILITY STUDY FOR DYKE MARSH DEMONSTRATION AREA, POTOMAC RIVER, VIRGINIA, by Palermo and Zeigler, November 1976

Appendix F

Typical Stone Breakwater Section Marine Mattress General Information

Dyke Marsh Restoration Project, Belle Haven, Virginia – Final Geotechnical Report

Final Geotechnical Report Dyke Marsh Restoration Project

Belle Haven, Virginia July 2017

1. PROJECT LOCATION AND DESCRIPTION: The proposed Dyke Marsh Restoration project is located in Belle Haven, Virginia one mile south of Alexandria, Virginia along the west bank of the Potomac River just south of the Woodrow Wilson Bridge. The project consists of constructing a 1550 foot stone breakwater structure to elevation +5.5 feet mlw and infilling the shoreline area with fill materials to restore the shoreline back to its original 1930’s footprint. A Location Map and General Plan are included in Appendix A.

2. GEOTECHNICAL SCOPE OF WORK: The purpose of this report is to establish the subsurface conditions and provide an estimate of the depth of failure and corresponding mudwave action in the very soft unstable fine grained sediments during the construction of the stone breakwater and anticipated settlements after the completion of the breakwater.

3. PREVIOUS 1976 INVESTIGATIONS: Three borings DM-1, 2, and 3 were conducted in January 1976. The borings were completed in 7 to 10 feet of water from a barge and taken to a depth of 50 feet below the mudline. Three-inch undisturbed tube samples were taken in the fine grained materials and split spoon samples were taken in the underlying cohesionless soils utilizing the standard Penetration Procedure (SPT) per ASTM D 1586 as discussed below for phase 1 subsurface investigations. The hammer type is unknown.

Boring locations, foundation boring logs, general soil profile and corresponding laboratory soil testing results are contained in Appendix E. Reference Technical Report

D-76-6 FEASIBILITY STUDY FOR DYKE MARSH DEMONSTRATION AREA,

POTOMAC RIVER, VIRGINIA, by Palermo and Zeigler, November 1976.

4. PHASE 1 SUBSURFACE INVESTIGATIONS: Subsurface explorations via the Standard Penetration Test method were completed in October/November 2015 by the Baltimore District U.S. Army Corps of Engineers Field Exploration Unit utilizing a CME-45 rig mounted on a barge in the Potomac River. Seven drill holes were completed to depths ranging between 16.5 to 45 feet below the mudline (27.5 to 51 feet below the water line). Soil samples collected during the explorations program were accomplished using the Standard Penetration Test Procedure (SPT) per ASTM D 1586 using a 1-3/8-inch ID x 2-foot 8-inch long split spoon sampler. Sample spoons were advanced by a 140-pound automatic hammer dropped 30 inches. The number of blows required to advance the sample spoon in intervals of 6 inches (for a total 18 inch length sample) were recorded on the logs with the sum of the latter two blow counts (final 12 inches of penetration) referred to as the “N” value. The SPT provides soil samples to evaluate the distribution of soil types and in-situ moisture contents throughout the project area and blow count data which indicates the relative density and consistency of the granular and cohesive soils respectively. Borings were advanced by means of the Standard Penetration Test (SPT) method at 2.5-foot intervals for the first 30 feet and then at 5.0-foot intervals for the remainder of the hole and power augured between samples utilizing 2 ¼ inch ID hollow stem augers. The boring logs are contained in Appendix B.

Based upon these seven borings, the soils within the upper 9 to 27 feet below the mudline consisted of very soft unstable fine grained cohesive sediments consisting of high and low plastic silts and clays (CL, ML, CH and MH) with natural water contents (w %) equal to or exceeding the Liquid Limit (LL) and corresponding N-values being generally weight of rod (WOR) or weight of hammer (WOH). Undisturbed samples of these very soft fine grained cohesive soils could not be collected due to the soils being too soft and saturated to remain in the Shelby Tube during sampling. Therefore to obtain settlement and strength parameters of these very soft cohesive soils, Flat Plate Dilatometer tests (DMT) along with undisturbed sampling utilizing an Osterberg sampler were conducted as described in paragraphs PHASE 2 SUBSURFACE INVESTIGATIONS.

5. PHASE 2 SUBSURFACE INVESTIGATIONS: Phase 2 subsurface investigations consisted of twenty-three Flat Plate Dilatometer tests (DMT) and four undisturbed samples utilizing the Osterberg sampler completed by the Baltimore District U.S. Army Corps of Engineers Field Exploration Unit in May/August of 2016. The DMT’s were completed in accordance with ASTM D 6635 utilizing a CME-45 skid rig mounted upon a barge in the Potomac River. The DMT was advanced to a depth of 30.2 feet or until refusal was encountered, which ever occurred first, resulting in depths ranging from 8.5 to 30.2 feet below the mudline with elevations ranging between -10.1 to -39.4 mlw. In general the DMT consists of a stainless steel blade having a flat, circular expandable steel membrane mounted flush on one side. The DMT is hydraulically pushed into the ground and the test performed at depths of 8-inch increments. The expandable steel membrane is inflated and the pressures required to mobilize two pre-established strain levels are recorded. The DMT results are contained in Appendix C and are presented graphically as “measured” parameters and “interpreted” parameters based upon published correlations.

Five representative undisturbed samples utilizing the Osterberg sampler were taken in the very soft fine grained cohesive materials adjacent to DMT’s-2A, 3, and 5A (designated as SDMT-2A, 3, and 5A) in August 2016 to conduct undisturbed laboratory consolidation and shear strength testing as addressed in paragraph LABORATORY TESTING. Depths of the undisturbed samples are illustrated in the following table Osterberg Sample Depths:

Osterberg Sample Depths

SDMT Depth below Mudline (feet)

2A – Shelby 1 5.0 – 7.0

2A – Shelby 2 9.0 – 11.0

3 – Shelby 1 5.0 – 7.0

3 – Shelby 2 12.0 – 14.0

5A – Shelby 1 12.0 – 14.0

A Subsurface Exploration Plan illustrating the locations of the 1976 Previous Explorations, Phase 1, and Phase 2 Explorations are contained in Appendix A.

6. LABORATORY TESTING: All laboratory soils testing was completed by the Baltimore District Corps of Engineers Materials and Instrumentation Unit in accordance with the appropriate ASTM methods with the exception of the Unconsolidated Undrained (UU) Triaxial Compression tests which were conducted in accordance with ASTM D2850 by the Robert B. Balter Company. The results of all laboratory soils testing are presented in Appendix D and reflected on the boring logs where applicable. A summary of selected Atterberg limits (LL, PI), moisture contents (w%), Constrained (Tangent) Modulus (M) and undrained shear strength (Cu) test results are illustrated below in Table Summary of Selected Soil Properties.

Phase 1 laboratory soil testing consisted of visually inspecting the SPT samples and assigning a Unified Soil Classification System (USCS) classification by an experienced laboratory technician. Index properties of selected samples representative of soil stratification were determined by performing mechanical sieve analysis, Atterberg limits, and in-situ water contents.

Phase 2 laboratory soil testing consisted of Consolidation and UU Triaxial Compression tests conducted on undisturbed samples to evaluate the compressibility and shear strength characteristics of the very soft cohesive materials. The results of the Consolidation and UU Triaxial Compression tests were also used to validate the undrained shear strength (Cu) and constrained (tangent) modulus (M) values interpreted from the DMT in-situ tests. A comparison of these test results are summarized below as Lab/DMT in the last two columns of Table Summary of Selected Soil Properties; the values obtained from laboratory testing compared very well with those interpreted from the DMT therefore validating the DMT results. It shall be noted that although the undisturbed samples were obtained adjacent to the DMT, slight variation in the mudline depth and stratum is anticipated. In addition, although the Osterberg sampler was used to obtain a high quality undisturbed sample, the soil sample can be assumed to be subjected to some degree of disturbance due to the very soft and unstable nature of the fine grained cohesive soil sediments and as reflected by visual inspection of the laboratory consolidation test curves.

Laboratory shear strength (Cu and φ) and settlement parameters (M) are determined from a small soil sample recovered from a specified depth and location. These soil parameters are then assumed to be identical throughout the remainder of the stratum. However, the DMT provides shear strength and settlement parameters at 8-inch intervals throughout the entire depth of the investigation providing a more accurate and representative presentation of the stratum as indicated in the DMT results contained in Appendix C.

Since the values obtained from laboratory testing compared very well with those interpreted from the DMT therefore validating the DMT results as discussed above, the DMT test results were used to estimate the shear failure and corresponding mudwave action of the very soft fine grained cohesive foundation materials during the placement of the stone breakwater and settlements following completion of the breakwater.

Table Summary of Selected Soil Properties

Location Depth Below

Mudline (feet)

USCS

Classification

Natural Moisture Content (w %)

Liquid Limit

(LL)

Plasticity Index

(PI)

Cu (bar)

Lab/DMT

M (bar)

Lab/DMT

DH-1 13.5 - 15.0 CL 33.6 32 13

DH-2 21.0 - 22.5 MH 85.9 85 47

28.5 - 30.0 MH 71.2 69 34

35.0 - 36.5 MH 53.1 54 24

DH-3 16.0-17.5 CH 92.9 84 47

21.0 - 22.5 CH 91.2 86 49

DH-4 11.0 - 12.5 CH 118.7 91 52

16.0 - 17.5 MH 100.2 88 49

23.5 - 25.0 CH 86.2 88 50

28.5 - 30.0 CL 44.8

DH-5 9.0 - 10.5 CH 104.2 80 46

16.0 – 17.5 MH 81.3 73 37

23.5 – 25.0 CH 76.4 77 44

DH-6 13.5 – 15.0 MH 126.7 95 54

SDMT-2A 5.0 - 7.0 MH 73.9 72 37 0.10/0.10 4.0/11.0

SDMT-2A 9.0 - 11.0 MH 77.9 65 30 0.08/0.10 4.0/15.0

SDMT-3 5.0-7.0 MH 99.7 62 29 0.10/0.08 2.5/10.0

SDMT-3 12.0 – 14.0 CH 65.6 50 22 0.07/0.09 5.5/13

SDMT-5A 12.0-14.0 MH 81.6 61 28 0.10/0.10 4.5/13

*0.10 bar = 208 psf; 0.08 bar = 188 psf; 0.08 bar = 167 psf

7. REGIONAL GEOLOGY: The Dyke Marsh Restoration project located along the west bank of the Potomac River in Belle Haven, Virginia lies within a geologic area known as the Atlantic Coastal Plain Physiographic Province of Virginia. Normally consolidated recently deposited alluvial soils overlie the highly preconsolidated Patapsco clay (also referred to as the Potomac clay). The sedimentary sequence shows predominately sands and gravels, with lenticular interlayered units of silt and organic clays. This reflects rapidly changing conditions in the depositional environment, attributed to tidal fluctuations in the Potomac River and intermittent rapid runoff from Hunting Creek.

Much of the upper sands and gravels have been removed from mining operations that occurred in the 1930’s up through the 1970’s and replaced with very soft fine grained cohesive sediments. Rock is at a depth of several hundred feet. This Patapsco formation is part of the Potomac Group of the Cretaceous Age. Soil stratigraphy is discussed in detail in paragraph SOIL STRATIGRAPHY.

8. SOIL STRATIGRAPHY: A general description of the soil conditions encountered within the project limits is discussed below. These stratum designations do not imply that the materials encountered are continuous across the site. Actual soil conditions between SPT and DMT locations may differ from these descriptions.

(STRATUM A): Stratum A consists of up to 27 feet of sediments below the mudline that consist of very soft under to normally consolidated cohesive soils consisting of high and low plastic silts and clays (CL, ML, CH and MH) with isolated lenses of sand. The N-values within this stratum generally range from weight of rod (WOR) to weight of hammer (WOH) with natural water contents (w %) equal to or exceeding the Liquid Limit (LL).

Per the DMT, generally these very soft cohesive soils are given a soil type designation of “MUD” with undrained shear strengths less than or equal to 0.11 bar (230 psf), constrained (tangent) modulus values generally less than 20 bar and thrust values less than 200 kilogram-force (440 lb-force). Undrained shear strengths, constrained modulus and thrust values generally increase slightly at the bottom (or within isolated lenses) of the stratum and are characterized by a soil type designation of silt, silty clay and sandy or clayey silts.

STRATUM B: The soils below Stratum A consist of loose to very dense granular soils consisting of silty and clayey sands (SM and SC), poorly graded sands (SP) and well graded and silty gravels (GW and GM) with N-values ranging from as low as 4 to greater than 50 in the gravelly soils. Two of the seven drill holes, DH’s-2 and 3, encountered the underlying Potomac clays at depths of approximately 35 feet below the mudline. The five other drill holes terminated in the sands of Stratum B.

The DMT was advanced to depths ranging between 8.5 to 30.2 feet below the mudline with elevations ranging between -10.1 to -39.4 mlw. All DMT tests were terminated in either Stratum A or B. Per the DMT, generally these cohesionless soils are given a soil type designation of sand, silty sand, or sandy silt with friction angles ranging between 26 and 40 degrees and constrained (tangent) modulus values ranging between 24 and 700 bar.

9. MUDLINE ELEVATION: The mudline elevation at the time of DMT testing varied from elevation -0.9 feet at DMT 14 to -10.2 feet at DMT 7A. The mudlines varies throughout the site and is the result of previous mining operations, sediment transport and possibly erosion. The mudline elevation was computed by subtracting the water depth from the tide elevation obtained from the Washington DC tidal station at the time of DMT testing.

Mudline elevations at the locations of the DMT’s are summarized below in Table Mudline Elevation @ Time of DMT.

Mudline Elevations @ Time of DMT

DMT Mudline Elevation

(feet) 1 -2.0

2 -9.8

2A -9.4

3 -10.0

4 -9.2

5 -7.9

5A -6.4

6 -3.3

6A -8.6

7 -4.9

7A -10.2

8 -2.6

9 -3.7

10 -4.7

11 -3.6

12 -1.9

13 -5.3

14 -0.9

17 -4.5

18 -10.1

19 -8.9

20 -6.1

21 -7.7

10. ESTIMATED FAILURE DEPTH (MUDWAVE) OF FOUNDATION SOILS: It is our understanding that the Stone Breakwater will be constructed within the vicinity of DMT’s

1, 2, 2A, 3, 4, 5, 5A, 6, 6A and 7A. As previously discussed, Stratum A consists of up to 27 feet of very soft under to normally consolidated recently deposited alluvial cohesive soils with N-values ranging from weight of rod (WOR) to weight of hammer (WOH) and natural water contents (w %) equal to or exceeding the Liquid Limit (LL). Due to the unstable nature of these cohesive soils, general shear failure and corresponding mudwaving is anticipated during placement of the stone breakwater.

A bearing capacity analysis utilizing Terzaghi’s General Shear Case was performed to estimate the depth of failure to better define the limits of the mudwave. The most critical “usual” failure condition will occur during construction when the soft fine grained cohesive soils are subjected to unconsolidated undrained shearing. The most critical “unusual” failure condition may occur shortly after construction when the foundation soils have not yet consolidated and the breakwater is constructed during a high tide followed by a sudden drop in water to low tide exposing the majority of the breakwater above the water line and therefore subjecting the foundation soils to its first highest loading condition also resulting in unconsolidated undrained shearing. Therefore, undrained shear strength values (Cu) obtained from UU triaxial compression tests (Q-test) and from the DMT results were used in the bearing capacity analysis.

The stone breakwater structure will be constructed by first placing a 55 foot wide marine mattress system upon the mudline and stacking to an elevation of -5.0 feet mlw for a length of 1550 feet. Following the placement of the marine mattress units to elevation -

5.0 feet mlw, riprap and armor stone will be placed upon the marine…