Sec Form 4 Filing - Simonelli David E @ Great Lakes Dredge & Dock CORP - 2020-03-08

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Simonelli David E 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) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) President - Dredging Division (Last) (First) (Middle) C/O GREAT LAKES DREDGE & DOCK CORP., 2122 YORK ROAD, 2ND FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 03/08/2020 (Street) OAK BROOK, IL60523 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 03/08/2020 A 65,663 A 369,722 D Common Stock 03/08/2020 A 14,591 A 384,313 D Common Stock 03/08/2020 F 13,231 D $ 8.99 373,696 ( 3 ) 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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 of Derivative Security: 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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Simonelli David E C/O GREAT LAKES DREDGE & DOCK CORP. 2122 YORK ROAD, 2ND FLOOR OAK BROOK, IL60523 President - Dredging Division Signatures /s/Kathleen M. LaVoy, by Power of Attorney 03/10/2020 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents restricted stock units awarded pursuant to satisfaction of performance conditions per the terms of the Special Incentive Program granted on March 8, 2018. These units vest on December 31, 2020. ( 2 )Represents shares awarded pursuant to satisfaction of performance conditions per the terms of Mr. Simonelli's performance-based restricted stock units granted on March 8, 2018. ( 3 )This filing also adds 2,614 shares of Common Stock acquired under the Company's Employee Stock Purchase Program.

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).

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