SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* Mackie Douglas B (Last) (First) (Middle) GREAT LAKES DREDGE & DOCK CORPORATION 2122 YORK ROAD (Street) OAK BROOK IL 60523 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Great Lakes Dredge & Dock CORP [ GLDD ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 03/08/2011
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/08/2011		S		45,000(1)	D	$7.92(2)	215,346	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. The sales reported were effected pursuant to a Rule 10b5-1 trading plan adopted by Mr. Mackie on February 24, 2011.

2. Represents weighted average sale price. The sale price range is $7.74 to 8.03. Upon request by the Commission staff, the issuer or a security holder of the issuer, the reporting person will provide full information regarding the number of shares sold at each separate price.

	/s/ Kathleen M. LaVoy, by power of attorney	03/10/2011
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

POWER OF ATTORNEY

	Know all by these presents, that the
undersigned hereby constitutes and appoints each of
Kathleen M. LaVoy and Katherine M. Hayes, or either of
them signing singly, and with full power of
substitution, the undersigned's true and lawful
attorney-in-fact to:

(1)       execute for and on behalf of the
undersigned, in the undersigned's capacity as an
executive officer and/or director of Great Lake Dredge
& Dock Corporation (the "Company"), Forms 3, 4, and 5
in accordance with Section 16(a) of the Securities
Exchange Act of 1934 and the rules thereunder, and any
other forms or reports the undersigned may be required
to file in connection with the undersigned's
ownership, acquisition, or disposition of securities
of the Company, including, without limitation, Form
144, in accordance with Rule 144 under the Securities
Act of 1933;

(2)      do and perform any and all acts for and on
behalf of the undersigned which may be necessary or
desirable to complete and execute any such Form 3, 4,
or 5, or Form 144, complete and execute any amendment
or amendments thereto, and timely file such form with
the Securities and Exchange Commission and any stock
exchange or similar authority; and

(3)       take any other action of any type whatsoever
in connection with the foregoing which, in the opinion
of such attorney-in-fact, may be of benefit to, in the
best interest of, or legally required by, the
undersigned, it being understood that the documents
executed by such attorney-in-fact on behalf of the
undersigned pursuant to this Power of Attorney shall
be in such form and shall contain such terms and
conditions as such attorney-in-fact may approve in
such attorney-in-fact's discretion.

	The undersigned hereby grants to each such
attorney-in-fact full power and authority to do and
perform any and every act and thing whatsoever
requisite, necessary, or proper to be done in the
exercise of any of the rights and powers herein
granted, as fully to all intents and purposes as the
undersigned might or could do if personally present,
with full power of substitution or revocation, hereby
ratifying and confirming all that such
attorney-in-fact, or such attorney-in-fact's
substitute or substitutes, shall lawfully do or cause
to be done by virtue of this power of attorney and the
rights and powers herein granted.  The undersigned
acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the
undersigned, are not assuming, nor is the Company
assuming, any of the undersigned's responsibilities to
comply with Section 16 of the Securities Exchange Act
of 1934 or Rule 144 under the Securities Act of 1933.

	This Power of Attorney shall remain in full
force and effect until the undersigned is no longer
required to file Forms 3, 4, and 5 and Form 144 with
respect to the undersigned's holdings of and
transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed
writing delivered to the foregoing attorneys-in-fact.

	IN WITNESS WHEREOF, the undersigned has
caused this Power of Attorney to be executed as of
this 3rd day of March, 2011.

         /s/ Douglas B. Mackie