A Report From the Field: Warrior River Coffer Dam Project

By Skip Ragsdale, Sunshine Supplies

APS distributors work with local, state and federal agencies, frequently, to find ways to benefit from polymer enhanced technology on a variety of sites.

In order to build a long bridge across the Warrior River, coffer dams were constructed around the concrete footings that would eventually became the base for the bridge supports. The area within the coffer dams contained loose rock and soil. To assure the bridge supports were solidly attached to the bedrock, the contractor must remove this loose material and anchor the footings into the bedrock. A clamshell bucket on a crane was used to remove most of the loose material, but eventually, another method would have to be used to remove what remained. An airlift was brought in to remove the last remaining material to assure solid attachment between the concrete footing and bedrock.

An airlift looks something like a very large candy cane. The 12” I. D. steel pipe has a long straight end and a 180-degree bend at the other. Close to the end of the long straight part is where compressed air enters the pipe. As air is pumped into the pipe, it rises toward the 180-degree bend and creates a suction that “pulls” sediment and rocks (up to 12” diameter) through the pipe and discharges them back into the river. Since this is not “new” material being placed in the river, this is acceptable; however, it is possible that the small soil particles could create a plume that would move with downstream with the river current. This is not acceptable because it could be a hazard to aquatic life forms.

The contractor contacted Skip Ragsdale of Sunshine Supplies, Inc. because of his successful past use of anionic polyacrylamide erosion/sediment control polymers, manufactured by Applied Polymer Systems (APS). A test of the onsite soil determined the correct powder form of APS polymer to use to flocculate out the small suspended solids from the discharge water in the airlift device. The powder was added to the water contained within the coffer dam and the airlift was used to mix them. When the airlift pulled the sediment off the river bottom and discharged it to an area surrounded by turbidity barriers, the sediment quickly dropped to the river bottom. Without the use of the Applied Polymer Systems anionic polyacrylamide powder, the sediment would likely have remained in suspension and producing a plume that would continue down river. By using the APS product, the sediment particles attached to each other, became heavy and dropped to the river bottom.

Click Here to visit the Sunshine Supplies website.