Dothan commissioners approved nearly $3 million for engineering work to close one wastewater treatment plant and expand another.

But eventually the commission will have to identify how the city will pay for the bigger project, which could cost at least $30 million. Sales taxes or a sewer fee increase seem to be their options.

The commission voted during their Tuesday meeting to award separate contracts for engineering services to construct a pipe line from Beaver Creek Wastewater Treatment Plant to Little Choctawhatchee Wastewater Treatment Plant, decommission the Beaver Creek plant and expand Little Choctawhatchee to handle the additional sewage from Beaver Creek. One contract was awarded to Barge, Waggoner, Sumner and Cannon Inc. for $1 million. A second contract went to Polyengineering Inc. for $1.9 million.

To cover the full $30-million cost of the project, the city will likely have to issue a bond early next year. At that point the city will have to dedicate a revenue stream to pay back the debt in payments of roughly $2 million a year.

Mayor Pat Thomas said no decision has been made, but the commission may consider using sales tax revenues or a graduated sewer fee increase that could be implemented over time.

Dothan City Manager Mike West said unless the city commission is willing to allocate revenues from a new 1-percent sales tax, an increase in sewer rates would be the most logical decision. Last year, the city lost money on its sewer system to the tune of about $3 million. So far this year, the city has earned about $2.5 million in revenues.

West said the city has bought enough land around Little Choctawhatchee to serve future needs.

“The big problem we’re going to have is technology is going to change,” West said. “What everybody has to realize is if environmental requirements change, a process may have to be modified and that takes money to do.”

The Beaver Creek plant was built in the late 1950s and is the oldest treatment plant in Dothan.

Restrictions are expected to be tightened on the plant due to overflow problems during heavy rains that cause the plant to go over environmental permit limits. Beaver Creek — the small stream into which discharge from the plant is pumped — is considered an endangered stream by the Alabama Department of Environmental Management.