The Inner Harbor Launch Ramp, located at the mouth of the Snake River in Nome, Alaska, required dry repair work. Rather than employing traditional sheet-pile methods, the contractor selected an AquaDam® solution. In this stage of the project, the excavator is transporting the AquaDam® to the designated launching point, also referred to as the starting bank.

Larger AquaDams® are shipped rolled in a carpet-like configuration around a central log, secured with a protective covering and equipped with lifting straps for handling. To prepare for installation, the crew constructed a starting bank using super sacs. This setup ensured that the AquaDam® remained elevated and protected from direct contact with the rip rap armoring.

The 16ft tall, 33ft wide when fully filled, 261ft long single closed end (SCE) AquaDam® has been placed at it’s starting bank. A SCE AquaDam® requires a starting bank to keep its open end and fill-tubes higher in elevation than the body of the AquaDam®. The open end and fill-tubes of a SCE AquaDam® must stay elevated higher than the full height of the dam along its given path. An AquaDam® will only reach its full height at the lowest elevation along its given path.

t this stage, the crew must secure the open end of the 16ft tall SCE AquaDam® to prevent movement during deployment. It must be extended sufficiently to clear the super sacs on the far side, ensuring that the central log does not become obstructed or caught between the super sacs during installation.

Workers utilized heavy lifting equipment in conjunction with straps secured around the ends of the central log to maneuver the AquaDam®. This method enabled the crew to safely lift and unroll the structure beyond the line of super sacs, guiding it smoothly into the water for proper placement.

The roll end of the AquaDam® can now be lowered into the water, allowing the crew to begin filling the unit with water.

A key advantage of the AquaDam® lies in its construction using lightweight, flexible materials. This design enables the structure to maintain buoyancy when empty in adequate water depths, allowing crews to easily maneuver and precisely position the structure. Furthermore, this flexibility ensures the unit conforms optimally to irregular substrate contours, which is essential for achieving the watertight seal required for effective de-watering.

Following the placement at the starting bank, the 16ft SCE AquaDam® has been securely positioned and confirmed to be operationally ready. Personnel can now commence the controlled introduction of water to initiate the inflation process, which will transition the flexible structure into a solid, functional barrier capable of isolating the repair zone.

Workers placed additional super sacs along the sheet-pile wall at the designated ending bank of the AquaDam®. This strategic measure provides seepage control at the critical 90-degree junction where the sheet-pile meets the riverbed. Once fully deployed, the AquaDam® will assume an almost U-shaped configuration, consistent with the project’s design specifications and operational requirements.

Super sacs were positioned in front of the sheet-pile wall, each equipped with a float and rope to facilitate retrieval after project completion. The closed end, or roll, of the 261ft long SCE AquaDam® will rest directly against the super sacs and the sheet-pile, ensuring a secure termination point for the installation.

For this project, the crew utilized two 6in pumps to fill the AquaDam®. The overall pumping capacity directly determines the time required to complete the filling process, as the rate of water delivery governs how quickly the structure can achieve its full operational height.

The 16ft SCE AquaDam® is currently undergoing the controlled water inflation process. As the structure begins to take shape, the crew will soon initiate the critical maneuver to position the roll end. This active shaping is necessary to commence the turn that will form the final U-shaped configuration.

To achieve precise alignment during deployment, the crew implemented a rigging system by attaching a series of manipulation ropes to the AquaDam®. This system is instrumental in providing the project personnel with the necessary means to exert controlled directional force on the core log and roll end. This effort is critical for guiding the structure as it commences its turn, thereby establishing the installation trajectory desired to achieve the necessary U-shaped configuration.

Maintaining the positional stability of the AquaDam® during the initial filling phase is essential, particularly in environments with moving or flowing water. To counteract hydraulic forces acting on the structure, anchors or heavy external masses should be employed as secure tie-off points. This technique provides critical stability until the unrolled body of the dam rises above the surrounding water level, ensuring controlled deployment and proper alignment.

An empty AquaDam® will float in sufficiently deep water, simplifying the installation process. As water is introduced, the structure gradually unrolls. Turns can be achieved by pulling on either side of the roll or log with ropes, often coordinated with a reduction in pumping power to the fill-tube located on the inside of the turn. It is essential to remember that water will always seek the lowest point, a principle that governs the AquaDam®’s behavior during deployment.

This AquaDam® is being installed in a U-shaped, horseshoe configuration. The system’s flexibility allows it to be easily maneuvered during installation to accommodate varying angles. Turns can be achieved by adjusting the pump(s) supplying the fill-tube on the inside of the turn, or by rotating the dam using ropes attached to the edges of the central beam and anchored onshore.

Workers pull on the greater harbor side of the AquaDam® roll (left side in this photo) to unroll the material ends up where it is needed. For a U-shaped configuration cofferdam, when using an AquaDam®, the required length must be measured along the outer perimeter of the intended layout.

he 16ft tall SCE AquaDam® has been unrolled to the ending bank on the right, where it abuts the super sacs and sheet-pile wall. A small portion of the dam remains rolled on the central beam, a positive indication, as having extra length provides added flexibility during installation.

The 16ft tall, 261ft long SCE AquaDam® is now in place and nearly fully filled. Excellent work on the installation!