AUGUSTA — Residents with their own wells and septic systems could be charged fees for stormwater, under one option Greater Augusta Utility District officials are considering to deal with the cost of handling stormwater in Augusta.

Ken Knight, chairman of the district’s board of trustees, said at an annual planning meeting of the trustees Wednesday, attended by many local officials, “One of the options (to pay for stormwater handling costs) that’s going to be thrown on the table is a stormwater charge for people” who aren’t on the district’s water or sewer system.

He said the district is challenged by the cost of handling stormwater, some of which enters the sewer system and thus requires treatment before it may be released into the Kennebec River.

Andy Begin, the district’s assistant general manager, acknowledged that charging a stormwater fee to Augusta residents with their own wells and septic systems, who are thus not current ratepayers, could draw a negative reaction.

“We know it’s not a good political sell, to just start sending people a bill,” Begin said.

Knight noted discussion about rates and fees is premature and the district would work with the city before making changes to rate structures for its services, which include stormwater, drinking water and sewer service.

Knight said the district has the second-highest amount of stormwater pipes in the state, second to only Portland, in part because the district handles stormwater on both sides of the Kennebec River, which he said is rare for a single district.

“It’s not typical that a city is on both sides of a river,” Knight said. “It’s a challenge. We own both sides of the river and only have so much population” to pay for the cost of handling the stormwater.

Part of the cost of handling stormwater is the cost of trying to prevent combined sewer overflows into the Kennebec River, which occur when stormwater infiltrates the sewer system and, during major rainstorms, can overwhelm the system’s ability to treated the combined flow, causing some of it to overflow into the river.

One district proposal meant to help address such overflow is the construction of a million-gallon, roughly 100-foot-diameter concrete tank that would hold a combination of stormwater and sewage on Greater Augusta Utility District land next to the city’s East Side Boat Landing on the Kennebec River.

Brian Tarbuck, the district superintendent, said that would be the most affordable option, at a cost of about $1 per gallon of capacity, versus the approximately $5-per-gallon capacity cost of building an underground tank. He said the tank probably would cost about $1.5 million when all costs are included.

City officials have expressed concern about the visual effect of such a large tank so close to the boat landing, as well as its potential visibility from the Kennebec River and from the downtown area across the river, which has been the focus of extensive redevelopment efforts in recent years.

District trustees said the district would seek to have the tank situated as low as possible on the site, without taking on the major added cost of burying it underground, and would be creative in finding ways to make the tank blend in so it wouldn’t be an eyesore or a visual blemish prominent from the river or the downtown area just beyond it.

They said the district has many options that could help improve the proposed tank’s appearance, which could include having a brick facade on it, or screening it with trees so it wouldn’t be visible from across the river.

“It should fit in there nicely,” Tarbuck said of putting the tank on district property at 12 Williams St. “The question is what is it going to look like.”

The proposal is the district’s latest step in an ongoing, multimillion-dollar effort to install systems to prevent the overflow of sewage into the river during major rainstorms. The goal of adding the new tank to the district’s existing infrastructure would be to catch overflow during heavy rainfall and hold it in the tank until the flow subsides. Once the storm subsides and the plant is functioning normally, the fluid would be released from the tank and sent to the treatment plant.

In 2012 and 2013, the utilities district, in a $15 million project, installed two massive, 670-foot-long storage tanks under Mill Park to collect combined sewer overflow on the west side of the river. The district has another underground storage tank under a portion of the Kennebec River Rail Trail that cost about $10 million. The proposed tank would be the last major piece of infrastructure needed to prevent most overflows and be in compliance with state Department of Environmental Protection requirements regarding overflows.

Begin said debt from past combined sewer overflow projects is part of what is now driving stormwater expenses.

He said the district has been working on complying with DEP mandates to prevent overflows for more than 30 years, and has a deadline of 2020.

Tarbuck said the good news is that the proposed tank would be the last such major tank the district will need to put in to help prevent combined sewer overflows, and satisfy state DEP mandates to reduce them. He said his predecessor, Dale Glidden, began working on reducing such overflows in the 1980s.

“It’s a long haul and we’re almost there,” he said. “It’s super-exciting for us.”

Tarbuck said construction ideally could start in about a year.

Keith Edwards — 621-5647

kedwards@centralmaine.com

Twitter: @kedwardskj