Tuesday, December 16, 2008
I've always been somewhat surprised by the Corps of Engineers continued use of PVC dumbbell waterstop in their flood control and dam projects. After Hurricane Katrina hit, and large portions of floodwall needed to be repaired or replaced, the COE's design still called out for this largely out-dated style of waterstop. Dumbbell waterstop functions like a cork in a bottle, with the large end bulbs simultaneously acting as both anchors and internal dams. Historically, dumbbell waterstop is one of the leakiest varieties of waterstop, as the large end bulbs when pulled under tension distort to an elliptical shape, while the concrete cast against them remains in a round shape and therefore creates an annular void for water to migrate through.
Now, large portions of the rebuilt floodwall in Kenner, LA are leaking and expensive repair procedures are taking place. I would imagine that simply by specifying a ribbed centerbulb waterstop this entire failure could have been avoided.