District Divers work to repair aging wicket dams

Corporate Communications
Published Jan. 2, 2013
John Snell, diver and lock and dam operator at Starved Rock, begins his submersion to pull bearings on the wicket dam in preparation for dewatering operations.

John Snell, diver and lock and dam operator at Starved Rock, begins his submersion to pull bearings on the wicket dam in preparation for dewatering operations.

Eighty years of wear and tear can cause significant stress to any man-made structure. The wicket dams on the Illinois River at Peoria Lock and Dam and Lagrange Lock and Dam have weathered 80 years of relentless currents, barge traffic and the daily rigors of operation. The wicket dams have maintained their functionality through the decades thanks in large part to the efforts of the crews tasked with their upkeep. Crews like the District’s dive team.

From August until December, dive crews are working at the Locks and Dams at Peoria and La Grange. Their mission is to stabilize the aging wicket dams so that the structures can continue to outlive their intended life cycle. During October, a crew of 10 or 12, made up of divers, boat operators and crane operators, has been working on the wicket dams at Peoria.

“We are working 11 days on and three days off, four months straight,” said Jim Punkiewicz, District dive team leader. “We did half of the wickets at Peoria in 2010. Three quarters of the dam at La Grange has been completed.”

Punkiewicz described wickets as “unique” when considering navigation structures. The purpose of wicket dams, as is the case with the more common roller dams, is to maintain pool elevation to make the river navigable. One of the primary differences between wicket and roller dams is that wicket dams can be laid down on the river bottom, enabling boat traffic to navigate the river without using the lock.

Each wicket is four feet wide by 16 feet tall and is constructed out of oak timber and steel plating. One wicket weighs 2.5 tons and 108 wickets make up the Peoria dam and 109 at La Grange. The wickets are raised and lowered with a back hoe. When the river levels are high, a maneuvering boat positions the back hoe to lower the wickets flush with the river bottom. The back hoe raises the wickets when the pool above the dam must be maintained to navigable levels.

Over the years, normal operations of the wickets have caused deterioration to the mechanisms that help raise and lower the structures resulting in destabilization. The Structures Unit and dive team are using a 72,000-pound dewatering bulkhead in order to access the blocks which hold the mechanisms in place. The divers are grouting behind the blocks which will help keep the wicket stable.

“It’s important for us to maintain the dam or we could end up losing the wickets, “ Punkiewicz said, “which will cause the pool level to drop.”

Losing the wickets is something that has occurred, according to Punkiewicz. That problem has usually happened when the wickets are laid down on the river bottom and boats are navigating over the wickets.

“When the wickets are down, wheel wash from the tow boats can suck the wicket out of its block if it isn’t stabilized,” he said. “There have been times when we have had to fetch the wickets down river.”

Punkiewicz said the work he and the crew are doing is taxing, both mentally and physically. Working around the dam presents a unique set of challenges because the work is being performed under water and on top. The first and foremost concern, as always, is safety.

“This is the most dangerous diving we do,” Punkiewicz said. “Typical diving conditions are dangerous enough but stabilizing the wickets means a whole new set of safety issues. On the upstream side of the dam you have the suction that creates havoc. On the low end there is always the chance of being blown downstream. Both situations could cause serious injury. But, we are all very safety conscious and everything we do takes safety into account beforehand.”

Along with safety, Punkiewicz said it is important for his dive team to have an attention to detail. Punckiewicz said there are several new divers on the team and they maintain that attention to detail by adhering to a very specific check list. There is not a lot of situational knowledge when it comes to working on the wickets so it is important for the team to stay focus on their processes.

“There are probably more than 40 steps to the process of setting the bulkhead and pulling it,” he said. “We have lot of steps to follow, whether it is placing our ladders in the water, sandbagging, pulling the needles or setting shutters – we stick to the process. In sticking to our check list, we are able to get anywhere from three to four sets of wickets grouted in our 11 day work period.”

Getting all 108 wickets stabilized will take the better part of four months but it is work that Punkiewicz said is critical.

“If you think about it, it is pretty amazing that these wickets have lasted this long,” he said. “A lot of people, both pleasure boaters and the barge industry, depend on these wickets being functional. Doing these dives presents a little more danger for us but it is work we are proud of.”

Teamwork is key, according to Punckiewicz. There is a lot of support from the river projects. “Without that support, it would be very difficult to complete the tasks in short time frame,” he said.