An annual study that looks at the effectiveness of Cranberry's sewage treatment plant shows that inflow will be beyond capacity within five years.
As a result, municipal officials now are in the early stages of planning a plant expansion and, at the same time, weighing whether the processing system for sewage treatment should be changed.
An annual report generated in the spring for the state Department of Environmental Protection looked at projected average daily flow of sewage to the Powell Road treatment plant for the coming five years. It showed that those average flows will exceed permitted limits of 4.5 million gallons per day by the end of that five-year period. Currently, the average flow is 3.2 million gallons per day.
Assistant township manager Duane McKee said the township has not exceeded the hydraulic capacity of the plant nor have there been violations in the quality of the treated sewage, known as effluent. That's with the current customer rate of 10,000 homes or businesses.
However, by 2017, things will be different, Mr. McKee said.
"We realized when we finished our comprehensive plan two years ago that this was coming. It's inevitable with the growth of the township," he said.
The township spends between $250,000 to $500,000 annually to detect unintentional stormwater flow into the treatment plant -- known as inflow and infiltration. The idea is that the township doesn't want to waste plant capacity treating rainwater in addition to sewage.
But, leaks in the system are inevitable, Mr. McKee said.
The plant, built in 2001, costs $2.2 million annually to operate.
Township supervisors agreed in August to begin a total evaluation of the treatment plant, looking both at capacity issues and the treatment process. When the plant was built, the township shifted to a treatment process that would produce sludge that was expected to have a beneficial reuse.
But that process turned out to have problems, including occasional odor that sparked complaints from neighbors. Also, the sludge is being placed in landfills because no one wants to buy it, Mr. McKee said.
"This system has its benefits and its cons, so we'll look at that," he said.
Also, the study will evaluate whether the plant should be expanded to handle the township's peak population, which is expected in 2030. Currently, Cranberry has about 30,000. By 2030, population is expected to hit about 50,000.
"We could do an intermediary expansion or build to handle peak flow. We'll evaluate the cost benefits of that," he said.
The Cranberry consulting firm HRG has been retained for $16,000 for the study. The evaluation process will take about a year, followed by two years of design, with construction to begin in 2016.
Karen Kane: email@example.com or 724-772-9180.