GARDINER — There will be winners and losers if city councilors decide to change the billing system the Gardiner Utility District uses for waste water usage.

Under the proposed change, customers would be charged a minimum flat rate in addition to their actual usage amount. Currently, the charge is an equivalent user rate formula, which is based on what a customer has the potential to use and what he or she actually uses.

The equivalent user rate formula was created so that those with the potential to contribute more waste to the system would be assessed higher fees.

But the proposed options are designed to allow those who actually use more to pay a higher rate in order to more closely reflect what they are contributing to the system.

“Some users will see a higher increase than 25 percent, and other (customers) will see an equivalent decrease in their rates,” City Manager Scott Morelli said.

The city hired Dirigo Engineering in Fairfield to come up with new sewer rate formulas. The firm will present three different scenarios at tonight’s council meeting.

Each scenario provides a flat fee that allows a certain amount of sewage to flow into the waste water system and a premium charged on any additional amount, Morelli said.

“The council will then decide to either remain with the current structure or select one of the three options and hold a public hearing on it later in the summer prior to official adoption,” Morelli said.

According to Dirigo Engineering, if the formula for determining sewer usage is changed, the annual bill for the Maine Turnpike Authority’s rest area and visitors center in West Gardiner could jump from $1,955 to $5,080.

On the other hand, several churches could see a decrease in their bills. For example, South Gardiner Baptist Church could pay $85 a year instead of its current bill of $307.

Gardiner’s Wastewater and Public Works Director Chuck Applebee said the equivalent user-rate-base formula was designed to help the city recoup its fixed costs and maintain the waste water system’s fixed costs — for heating and staff, for example.

“The usage part of the current sewer billing system was designed to pay for the variable cost of operating the sewer system such as pumping cost, electrical and equipment maintenance,” Morelli said.

Applebee said the city’s potential water usage calculation is based on Maine state plumbing code, which determines how much water a building of a certain size will use, on average. The calculations are those used to determine the leach field size for a private system and are very similar to design criteria used to size waste water plants.

The base fee, which does not include any usage, is $75.30 per equivalent user rate unit, or EUR.

The second part of the bill is usage: Customers are billed for each 100 cubic feet of water used.

Applebee said the usage part of the bill helps the city recoup variable costs to the waste water system, such as being able to provide more water when needed.

The usage fee is $1.91 per 100 cubic feet, added to the base equivalent user rate charge.

Applebee said the council is reviewing waste water rates to “ensure the billing system is fair and equitable for all users.”

A little over a year ago, the city contracted for a capital improvement plan and wastewater system assessment; connection fee evaluation, the fees charged to connect to the city sewer; and sewer rates options.

“The city solicited proposals for these three projects and hired Dirigo Engineering to perform them,” Applebee said. “The cost was approximately $25,000 for all three.”

Morelli said there shouldn’t be any cost to the city to switch over to a different rate formula, aside from a potential need to tweak its sewer billing software.

He said the city will receive the same revenue, whatever formula is chosen.

“It’s just a matter of slicing up the pie in a different way,” Morelli said. “We have a $32 million facility and $20 million more in sewer infrastructure that we need to maintain.

“This system is our line of defense between the Kennebec River and raw sewerage, and I think people would be surprised if they took a tour of the facility and saw how few people we actually have working there. It’s under recommended levels, but we have a very skilled, hard working crew at the plant and they do a great job at giving the sewer customers the most bang for their buck.”

The treatment plant also serves Randolph and Farmingdale, which contribute to the annual operating costs.

The council meeting is at 7 tonight at City Hall.

Mechele Cooper — 621-5663

mcooper@centralmaine.com