Dredging: The project involves dredging of approximately 25,000 cubic yards of contaminated sediment from Gloucester Harbor. The permits for the project have Time-of-Year restrictions which require that dredging be completed by February 14 of each year. To date, approximately 12,000 cubic yards of sediment have been dredged and loaded into scows. The wet sediment is allowed to settle within the scow, and the excess water is pumped to a water treatment system located on another barge near the Site. The water is discharged back into Gloucester Harbor after treatment. Approximately 1.5 million gallons of water has been treated to date. The sediment is then shipped via barge to a licensed facility in New Jersey for processing and disposal. Based on the current production rates, we anticipate that more than half of the total volume will be dredged and the dredging to be performed within the channel portion of Gloucester Harbor will be completed during the first work season. This will leave the remainder of the sediment near the shoreline area of the site to be removed during the second dredging season. The second dredging season will start in July 2016 and will continue into February 2017.
Dredge barge, with environmental controls around work area
Water treatment system
Dredge material deposited into scow
Scow with dredge material being transported off the Site for disposal
Scow alongside dredge barge
Solomon Jacobs Park Seawalls: This is one of the very technically challenging components of the project: it involves constructing a deep excavation support system behind the old granite block walls, removing the outer walls and the soil behind them, and then rebuilding a new seawall along the park perimeter.
Concrete and boulders removed during construction of excavation support system
Drilling the piles for the excavation support system
To allow access to this area for barge-mounted equipment, the timber pier in front of the park was removed in the fall 2015.
Removal of wooden piles supporting timber pier
Removal of timber pier decking
The excavation support system was completed in December and is visible from the harbor during low tide – it consists of a series of grout-filled steel piles, with steel plates below the high-water mark and wooden boards above, and steel rods connecting this system to weighted concrete blocks buried behind the plates. This support system allows the excavator to safely dig down to the depths required to pour concrete for the base of the new walls.
The excavation support system with drilled steel piles and lagging (wooden boards)
Removing the granite block seawall along the front of the park (December 2015)
Removing the granite block seawalls along the side of the slip (December 2015)
View of the park in early January 2016
Land-based operations supported by barge-mounted excavator and hydraulic hammer
Progression of the granite block seawall removal in January 2016
The concrete base of the new seawall will be almost 8 feet below the low tide mark, so much of the work must be coordinated with the tides and/or conducted under water, with divers inspecting the underwater work. As of late January, two-thirds of the concrete base has been completed, with the top surface just below the low water mark. It is anticipated that the entire concrete base will be completed, and that the bottom blocks of the granite block wall will start to rise above it, within the next several weeks.
Divers assisting with seawall reconstruction
Diver inspecting underwater construction
Pouring concrete for the base of the new seawall
Installing sandbags underwater in preparation for pouring the concrete base of the new seawall
The project is on track to complete reconstructing these seawalls by mid-May 2016. Over the next several weeks, steel piles will be installed in front of the new park seawalls to support a floating dock system for the City of Gloucester. The floats will be installed in May 2016 so that the park can re-open to use by the public in the summer.
Panorama of seawall construction activities (January 2016)
Harbormaster Building Seawall: The project involves building a new steel-pile-supported seawall in front of the Harbormaster Building extending onto Maritime Gloucester. This task is complicated by the age and condition of the existing granite wall, the presence of the building adjacent to the wall, the limited access available for large equipment, and extremely large boulders beneath the wall and directly in front of the wall that are submerged below the floor of the harbor. Initial piles have been installed in front of the Maritime Gloucester Boat House building and in front of one corner of the Harbormaster Building. Additional piles may be driven before February 14, when work will be suspended in accordance with the Time-of-Year restrictions. Starting in fall 2016, temporary in-water supports will be built so that specialized equipment can be used to complete the wall construction during the second work season.
Pile-driving in front of the Harbormaster Building
Pile driving in front of the Maritime Gloucester Boat House
United States Coast Guard: The rehabilitation of USCG Pier 2 is progressing, with new cross-bracing and fender piles installed at this location. Once complete, a temporary docking system will be built in front of Pier 2. This will provide an alternative location for the Coast Guard to dock their vessels during the second work season, when the nearshore sediments on their property are being dredged.
New cross-bracing beneath Pier 2
New fender piles at Pier 2
Maritime Gloucester: For safety reasons, the area in front of the Boat House is currently restricted to remediation crew and equipment. Therefore, a new landing and stairs were built on the north side of the Boat House for access into the building, and a new landing was added to one of the finger piers to allow gig rowers continued access to the harbor. Limited pile-driving may be conducted in front of the Maritime Gloucester seawall over the next several weeks, but most of the remediation at this property will be conducted during the second work season.
Construction of temporary gig rowers’ landing
New landing and stairs at Boat House
Environmental Controls: The orange booms floating around each of the remediation work areas in the harbor are the tops of in-water curtains designed to control turbidity (suspended particles in the water column) and sheens generated during dredging, drilling, pile driving, and excavation. Absorbent booms at the water surface act as a sponge to collect sheens, and are regularly inspected and replaced as necessary. The underwater curtains are also inspected for snagging on underwater obstructions, and are adjusted as needed to allow them to move freely with the tides.
Turbidity barriers being installed
Waterfront work area surrounded by environmental controls
Resuspension control system for dredge work area
Close-up view of resuspension control system before installation
Aerial view of project area. Orange environmental controls are visible in water around work areas.
Air monitoring station at US Coast Guard property next to park.
Throughout the work, regular readings are taken to monitor dust levels, noise levels and vibrations around the work area. The air quality is continuously monitored by an automated system of sensors to protect the safety of both the workers at the site and occupants of surrounding properties.