Upgrades to the water systems were required in two sections of the enhancement wetlands at the City of Arcata, California's wastewater treatment plant. AquaDams® were selected as the preferred cofferdams for this project.

The wetland water is commingled with treated wastewater and may therefore contain pathogenic organisms.

The first location requiring a cofferdam was Hauser Marsh, which needed to be de-watered to allow for the installation of an upgraded pumping system.

Before installing the AquaDam®, crews prepared the designated starting bank to facilitate a smooth and stable deployment.

When clearing the bank, it is essential not to excavate a deeper hole, but rather to create a smooth, flat surface to support the AquaDam®.

AquaDams® are shipped rolled up, similar to a carpet roll, secured around a wooden beam and wrapped in a protective covering. They are equipped with lifting ropes or straps for safe handling. The unit used at this site was a 4ft tall, 9ft wide (when fully filled), 213ft long single closed end (SCE) AquaDam®, which, when rolled up, fit in the bed of a full-sized pickup truck.

The 4ft tall SCE AquaDam® has been positioned correctly at its designated starting bank. Crews will now proceed to remove the lifting ropes and protective covering in preparation for deployment.

After removing the protective covering, workers unrolled a portion of the AquaDam® to access the fill-tubes.

The open end and fill-tubes of the 4ft tall AquaDam® were pulled up the bank and securely tied off. For successful installation of a SCE AquaDam®, it is essential that the starting bank positions the open end at an elevation higher than the dam’s full inflated height. The open end and fill-tubes must remain elevated above the maximum height of the AquaDam® along its entire deployment path. It is important to note that an AquaDam® will only reach its full height at the lowest point along its installed path.

Workers connected a discharge hose from a water truck to fill the AquaDam®. Per permit requirements, only potable water was authorized for use in filling the unit. Additionally, the water used to fill the dam was subject to testing and, if necessary, treatment prior to discharge or removal.

To allow the dam's body to fill and gain head over the surrounding water, workers restrained the roll of the 4ft tall SCE AquaDam® during its filling process.

Before installation, workers cleared a substantial amount of tule (hardstem bulrush) from the area. The root systems and underlying muddy substrate were significantly disturbed during the removal process.

As the 4ft tall SCE AquaDam® filled with water, the unit experienced displacement due to the previously disturbed mud and root systems.

Although it may be subtle, the AquaDam® is being installed on a cross slope that descends toward the camera operator. Notice how both the body of the dam and the rolled section lean slightly in that direction.

Workers continued filling the 4ft tall SCE AquaDam®, maintaining its placement as close as possible to the edge of the undisturbed tule plants.

Residual thick vegetation from the tule removal process exerted enough resistance to displace the AquaDam® into the adjacent body of water, despite persistent efforts by the crew to maintain its intended position.

Ultimately, the 4ft tall SCE AquaDam® was displaced too far into the work area, forcing workers to abandon the unit and initiate a new installation.

Due to the 4ft tall SCE AquaDam® being pushed off course and into the work area, workers are required to remove the unit.

To remove a SCE AquaDam®, it is advisable to first lower the water level inside the unit and secure the closed end. Workers then wrapped a lifting strap around the remaining rolled-up section and the wooden beam used for rolling the AquaDam®, enabling them to lift and pull the unit for removal.

A rope was secured to the strap encircling the closed end and rolled portion of the AquaDam®, allowing an excavator to assist in lifting and extracting the unit from the marsh.

The removal process should be conducted slowly and cautiously to prevent damage to the AquaDam® materials.

The excavator applied a low and steady pull to gradually remove the AquaDam® from the water, helping to retain fill water within the adjacent body of water during extraction.

A biologist was on site during the removal process to ensure that no aquatic organisms were inadvertently extracted from the marsh.

Workers extracted the AquaDam® from the marsh, positioning it on the adjacent parking lot.

As the AquaDam® was withdrawn, the open end and fill-tubes skimmed across the surface of the water, allowing the unit’s internal water to remain contained within the marsh.

After the AquaDam® was pulled out of the marsh, workers re-positioned the wooden beam to facilitate re-rolling of the unit. Ropes were tied and wrapped around the ends of the beam to aid in the re-rolling process.

Initially, workers manually pulled the ropes to initiate the re-rolling action.

After several initial rolls were completed manually, two excavators were employed to accelerate the re-rolling process.

The excavators lifted and advanced slowly in unison, allowing the AquaDam® to re-roll evenly and securely around the wooden beam.

Once the ropes reached their length limits, workers paused the operation to re-wrap them around the wooden beam before reattaching the ends to the excavators to continue the re-rolling process.

As re-rolling progressed, the AquaDam® roll began to loosen and bulk outward after several rotations, requiring periodic adjustments to maintain a compact and uniform wrap.

The ropes were fastened to facilitate a tighter winding of the roll as the excavators applied lift and tension.

Now that the roll has been tightened, workers have resumed the re-rolling process.

Workers continued re-rolling the 4ft tall, 213ft long SCE AquaDam®, gradually winding the unit onto the beam under coordinated tension and control.

With the 213ft long AquaDam® fully re-rolled and secured, the unit is now ready for loading and transport off site, marking a successful conclusion to a challenging operation. Well done, AquaDam® team!