Showing posts with label Corps of Engineers. Show all posts
Showing posts with label Corps of Engineers. Show all posts

Friday, October 01, 2010

Unique Waterstop System Utilized In Idaho Dam Rehab

In early summer season, the reservoir behind Dworshak is about 630 feet deep. At the bottom of the reservoir the water pressure is high. From the top to the bottom of the dam are large, solid, copper “waterstops” between the large concrete monoliths designed to prevent leaks between the monoliths and in the cracks. Since 2009, the District and a contracted architectural-engineering (A-E) firm have been studying and prototyping new urethane waterstop technologies for tall or “high-head” dams. This $1.3 million American Recovery and Reinvestment Act (ARRA) technology demonstration will lead to groundbreaking engineering research data for future high-head waterstop repairs at Dworshak and around the world. The urethane waterstop cylinders are being manufactured off site, and installation is expected to begin in late September 2010.

Tuesday, December 16, 2008

PVC Dumbbell Waterstop Leaks in Louisiana Floodwall

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.