A 6ft tall 13ft wide 40ft long single closed end (SCE) AquaDam® was installed within a tributary of Coyote Creek in Fremont, California. The cofferdam’s diversion system consisted of a 1,600ft long, 18in diameter welded HDPE pipe. This configuration is referred to as a flume-pipe diversion, with the AquaDam® deployed in a line configuration.

The 6ft tall SCE AquaDam® remains structurally intact following a significant precipitation event. The Fremont area recorded approximately 5in of rainfall within a 5-hour window, resulting in an upstream pool depth of nearly 5ft. This extreme hydraulic head has led to levels of seepage that exceed current management capacities.

While the substrate composition may not be immediately apparent, the AquaDam® is positioned on an aggregate base. Significant quantities of silt and mud have accumulated behind and beneath the unit; these materials were transported and deposited by the hydraulic pressure exerted by the seeping water.

Just upstream of the 18in pipe inlet, crews installed silt screens and constructed a temporary headwall to stabilize the diversion intake. The headwall was built using sandbags, concrete blocks, and Visqueen sheeting to control flow and reduce sediment intrusion.

The plan is to install an 8ft tall, 17ft wide (fully filled), 45ft long SCE AquaDam® between the temporary headwall and the existing 6ft tall AquaDam®. Before installation, the crew must remove all aggregate that had been placed to armor the canal within the dam’s intended footprint. Installing a cofferdam directly over this type of coarse material would create voids and pathways for nuisance water to infiltrate through the gaps between the rocks, compromising the effectiveness of the structure.

The presence of green vegetation and organic debris on the upper surface of the concrete blocks serves as a high-water mark, indicating that the water level reached at least that elevation during the peak of the rain event.

This material represents the aggregate stockpile that required removal from the canal to achieve an effective seal for the AquaDam®. Leaving this rock armor in place would have created void spaces and preferential flow paths, increasing seepage potential and reducing the overall performance of the cofferdam system.

The 6ft tall SCE AquaDam® is likely sitting on 2ft of aggregate, which allowed water to pass freely through the voids in the material. A SCE AquaDam® requires a stable starting bank to ensure that its open end and fill-tubes remain at a higher elevation than the body of the dam. For proper performance, the open end and fill-tubes must stay elevated above the full design height of the AquaDam® along its entire alignment. An AquaDam® will only achieve its full height at the lowest elevation point along its installed path.

For a flume-pipe diversion, Aqua Dam Inc. recommends installing a smaller AquaDam® beneath the pipe prior to placing the primary unit. This smaller dam is filled only after the main AquaDam® has been fully installed, allowing it to seal the area beneath both the pipe and the primary dam. AquaDams® are shipped rolled up like a carpet, wrapped in protective covering, and equipped with lifting straps for handling and deployment.

The crew has unrolled the 45ft long SCE AquaDam® across the canal, secured it to shoreline anchors, and begun the water-filling process. The fill-tubes, visible here as the black plastic with a white interior, serve as the primary intake points for introducing water into the dam. AquaDams® are constructed with extruded polyethylene inner tubes that provide a watertight internal seal, surrounded by a woven polypropylene outer sleeve that delivers structural strength during installation and operation.

The 8ft tall SCE AquaDam® has been filled to the elevation of the diversion pipe, and water has just begun to flow over the pipe within the dam. The temporary headwall and the existing 6ft tall AquaDam® played a critical role in stabilizing the pipe during this process. Without these supports, the lateral pressure generated by the rising water inside the AquaDam® would have pushed against the pipe and caused it to shift or slide out of position.

An aerial image from Google Earth Pro (June 2025) shows both SCE AquaDams® installed and functioning effectively.