Hermitage's crack inflow and infiltration team, which is sneaking around the city's subterranean passageways in search of leaking manholes and illegal connections to the sanitary sewer system, has hit proverbial gold.

The team has documented 107 manholes that are letting storm water into the system.

Sixty-two of them are around the area of Maple Road, East State Street and North Hermitage Road, and Hermitage Municipal Authority officials have pinpointed the cause: hydrogen sulfide gas from Clark and South Pymatuning Township, said Joe Pacchioni, consulting engineer.

The gas is typically found in "gray water" sewer systems such as Clark's, which takes away sewage water for treatment, while solids are collected in septic tanks to be pumped.

The gas eats away the concrete manholes, Pacchioni said Wednesday.

The problem has lessened this year. Pacchioni said he's not sure if that's due to the aerator Clark put on its system to release the gas, or if the unusual amount of rain the county got this year kept the gas down.