To keep water out of the way while crews replaced 100 feet of concrete liner and installed new piping, a 3-foot-high barrier spanning 30 yards was required to keep the jobsite dry. The City of Thousand Oaks, Calif., placed a 2.5-foot-tall portable dam slightly above the repair zone.
Matthew Wennerholm To keep water out of the way while crews replaced 100 feet of concrete liner and installed new piping, a 3-foot-high barrier spanning 30 yards was required to keep the jobsite dry. The City of Thousand Oaks, Calif., placed a 2.5-foot-tall portable dam slightly above the repair zone.

The City of Thousand Oaks, Calif., recently repaired a 1960s-era storm drain. To keep water out of the way while crews replaced 100 feet of concrete liner and installed new piping, a 3-foot-high barrier spanning 30 yards was required.

In addition to being unnecessary, erecting a permanent dam was too expensive and time-consuming. Public works decided to seek a temporary dewatering solution. Metal sheeting wouldn’t work because zinc or other hazardous metals could leach into the ground. Neither would sandbags; because they’re plastic, they’re considered hazardous material and must be disposed of as such. And, at $3 to $6 each, they would have cost $10,000.

Rather than stomach such a bill, the department pursued a third option.

You’d need 34 sandbags to build a 3-foot-high barrier spanning 30 yards. At $3 to $6 each, that’s a $10,000 dewatering solution. The same size AquaDam costs 60% less: $2,400.
USACE You’d need 34 sandbags to build a 3-foot-high barrier spanning 30 yards. At $3 to $6 each, that’s a $10,000 dewatering solution. The same size AquaDam costs 60% less: $2,400.

Granite Construction Inc. of Ventura, Calif., the city’s contractor, bought a temporary dam from AquaDam Inc. in Scotia, Calif. Made from extruded polyethylene inner tubing and woven polypropylene geotextile fabric, the product resembles a rolled-up inflatable bag. The roll is set at the top of a river bank and filled with water, which makes it unroll. If needed, turns can be formed by steering the roll with ropes. When work is completed, the dam is pumped down until the deflated “bag” is floating in the water. It’s then pulled out from its closed end, forcing the rest of the water to flow out through fill tubes at the open end. The dam can be rolled up on a wooden beam or log as it’s removed.

Dams are usually twice as wide as they are tall and up to 1,200 feet long. Connect multiple dams via a patented collar to form any length barrier required.