C&C Consulting Engineers was engaged by the Town of Rockport to review reconstruction of two of the jetties in Rockport Harbor and to monitor the stability of the improvements. The Bradley Wharf had recently collapsed, which prompted an engineering review of both structures. After receiving engineering recommendations, the Town had the Bradley Wharf reconstructed, and reinforcements were made to the toe of the T-Wharf. In both cases, the settlement was traced to a clay layer that extends under much of the harbor. The wharfs are built upon on this clay which is approximately twenty-five feet thick.
Shortly after construction was completed, further movement was suspected on the T-Wharf. C&C reviewed the prior design work and conducted a thorough field assessment. This design review found that the engineering was in accordance with acceptable practices. However, the fieldwork also confirmed the possibility of settlement in the T-Wharf and cracks in the concrete mortar used for re-setting the stonework on the Bradley Wharf.
Since completion of our initial review and report, the Town has engaged us on an annual basis to conduct a survey of multiple reference points on both wharfs, in an effort to ensure that the settlement problem has been solved permanently. We have produced annual reports to track the position of the reference points and to assess any deterioration in mortared joints between the stonework. Those surveys have detected progressive movement but so far, movement is well within allowable limits. The long-range plan is to continue the annual monitoring program until either the movement subsides or it becomes serious enough to affect the stability of the jetties.