X0306 4 2019-05-02 0 0001372020 Great Lakes Dredge & Dock CORP GLDD 0001658715 LaVoy Kathleen Mackie C/O GREAT LAKES DREDGE & DOCK CORP 2122 YORK ROAD OAK BROOK IL 60523 0 1 0 0 SVP & Chief Legal Officer Common Stock 2019-05-02 4 S 0 25000 10.808 D 100084 D The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $10.72 to $10.945, inclusive. The reporting person undertakes to provide to Great Lakes Dredge & Dock Corporation, any security holder of Great Lakes Dredge & Dock Corporation, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. /s/Kathleen M. LaVoy 2019-05-03