Client: Town of Harwich, MA
Project: Allen Harbor Dredge Project Harwich, MA
Date: October 2012-March 2013
Contact: Jim Merriam
Allen Harbor, Harwich, MA was originally to be bid as a hydraulic pipeline job but after further considering by the town it was agreed upon to allow mechanical dredging after the bidding was complete. Burnham was low bidder, but was forced to hold off on all work for more than a year for the permitting process to be complete. Burnham mobilized to Allen harbor in later October with the SAMSON III, pushboat STRIDER and two small 600 c.y. dump scows. The entrance to the harbor being just 70’ wide makes the work challenging upon entering and exiting.The project involved the mechanical removal of approximately 42,000 cubic yards of sediment and transport & placement at the Mass Bay Disposal Site (MBDS) Approximately 90 miles away. The unique features of Allen Harbor required Burnham Associates, Inc. (BAI) to utilize (2) 600 cubic yard split hull scows capable of maneuvering in and out of the extremes of depth and inlet configuration. With design depths at -6’ MLLW with one foot over-dredge, BAI utilized a DGPS program with tide data to insure compliance with overall project design. Due to the harsh weather encountered in 2012/2013 and distance to the disposal site, the initial schedule was adjusted through a Time of Year (TOY) extension request approved by MA DEP and National Marine Fisheries. The extension, although granted, required contingencies including a top to bottom silt curtain barrier and water quality and fisheries survey conducted to match dredge cycles. With these two TOY extensions, the project was completed on March 15, 2013, with removal volumes meeting design criteria.