Finding its level

Work on Chapman Dam moving along; 8 to 10 percent complete

Sheet piles driven 25 feet into the bed of Chapman Lake creates a coffer dam around the outlet pipe through the dam.

The water level at Chapman Lake is back up for a while.

Contractors are working on the outlet pipe through the dam.

According to Park Manager Tyson Martin, a more durable 21-inch high density polyethylene pipe will be fed through the existing 24-inch corrugated metal pipe.

A semi-circular coffer dam has been built, using sheet metal piles driven 25 feet into the lake bed, to keep water out of the work area.

The outlet pipe allows the lake to be lowered several feet below what can be done by the spillway alone. With the outlet pipe sealed off, water coming into the lake is flowing out at the spillway and the water level is up.

Martin said he expects the outlet pipe work to be complete within a few weeks and the lake level will again be lowered.

In the West Branch Tionesta Creek downstream, a temporary roadway has been built to allow movement of construction vehicles. The park’s bridge is not rated to carry vehicles so heavy, Martin said.

Farther down the creek, a check dam made of rock rubble slows the water flowing out of the spillway and allows sediment to drop out.

Coffer dams will be built again when the work moves on. Those structures will set off half of the spillway at a time. More stairs will be built in the spillway to slow the water moving out of the spillway, Martin said.

Martin addressed some of the common questions about the work.

“The dredging will not occur until next spring or summer,” Martin said.

“We think a vast majority of the fish made it downstream or upstream,” he said. There were some that were trapped in pools that were rescued and released. Some others died in the work.

Visitors are warned to keep their distance. “The contractor has asked people, for their safety, to stay out of the lake bed,” Martin said.

“Hunting areas and trails are all open. We’ve had plenty of people here hunting,” he said.

“Some popular parking areas are restricted,” Martin said. And that is a problem for Winterfest.

“The Winterfest committee is still deciding,” he said. Most of the facilities required for the event are available, but “it’s really the volume. We could have upwards of 15,000 people here over a three-day span. We don’t have anywhere to park them.”

The work is progressing as expected. “At the last job conference last week, they were 8 to 10 percent complete,” Martin said. “That’s on pace.”