OAKLAND TWP — Pennsylvania American Water is spending $10 million to upgrade the Oneida Reservoir Dam on Route 38.

Tyson Closer, project manager, said Tuesday the 94-year-old earthen dam will be encased in rolled concrete with a new spillway according to state Department of Environmental Protection standards.

The dam must be upgraded to withstand “probable maximum flood” standards of 26 inches of rain in 6 hours.

“In 1942, Smethport received 38 inches of rain in 4.5 hours, so we are going by measurements set by the National Weather Service,” Clouser said.

The concrete encasement will protect the dam from erosion that could occur during heavy rains.

The project is expected to be completed by November 2013.

So far, the dam has been stripped of its topsoil, as a new spillway with large concrete teeth at the bottom to dissipate the energy of water washing down the concrete sluice is being built.

Workers from the Casey Construction of Ivyland are constructing the spillway while shoring up the soil along the dam wall with special compacted sand.

“In the end, this dam will be able to withstand a 100-year flood and any water that should top it,” Clouser said.

In 2011, Pennsylvania American upgraded the Butler water system’s Thorn Run Reservoir in a similar $8 million upgrade.

The Oneida Dam project is the company’s largest capital investment for 2012.