WATERVILLE — The Kennebec Water District plans to start building a new $11.5 million business and operations center on Drummond Avenue in the spring if all goes according to plan.

The Planning Board on Tuesday voted 7-0 to approve the plans with conditions, including that it erect a fence around a retention pond on the property.

The water district’s general manager, Roger Crouse, said Wednesday that the district is awaiting site development and natural resources protection permits from the state Department of Environmental Protection and when they are received, work can begin.

“It’s going to be a great facility,” Crouse said. “It’s going to really meet our needs for 100 years and beyond.”

Owens McCullough, civil engineer with Sebago Technics Inc. said the 20,000-square-foot building would be on 15.5 acres and house what is now the water district’s business office on Cool Street and the operations center on South Street. The water district plans to sell the Cool Street site and will maintain a presence on South Street indefinitely, according to Crouse.

“The site is just inadequate for our needs going forward and has been inadequate for some time,” he said.

Crouse said Wednesday that the $15.8 million is the “best current estimate,” but the project will be put out to bid and he anticipates knowing the ultimate construction costs at the end of February.

As part of the plans, an 8,000-square-foot building would be constructed to house gravel and other materials and a 15,000-square-foot exterior space developed for pipe and yard materials storage. A parking lot with 43 spaces would be for employees, visitors and members of the water district’s Board of Trustees. The total developed area would be 10.88 acres. The water district has been on its current site for nearly 145 years.

“We’re hopeful that we can get into construction in the spring,” McCullough said. “Construction will probably take 14-15 months so we’d be looking for completion in 2023 and occupancy at that time. It’s pretty exciting. This has been a process that we’ve spent a lot of time working through and I think we’re there.”

An energy sustainable approach is being used for the building, with a geothermal system for heating and cooling. Nicole Rogers, an architect with SMRT Inc. Architects and Engineers, said the building is designed to be net-zero, with a solar array on its water treatment plant off site that would supply energy to all district buildings.

“The plan is to not have to use any fossil fuels and not have any utility bills,” Rogers said.

Planning Board member Bruce White said Tuesday’s presentation was great and he described a rendering of the building as beautiful.

“It’s fascinating, actually,” White said, “and it seems like 145 years is a long time in one place and hopefully, they’ll be there more than that in the new building once it gets approved.”

White asked if there will be an impact on rates because of the new development.

Crouse said there will be an impact, but he was not ready to announce rate increase plans. The investment needs to happen and it will be a much more efficient system for KWD, he said. White said he agreed.

“It sounds like a great long-term investment and I’m hopeful we accept it here tonight,” he said.

After urging by some board members to fence a retention pond on the property, Crouse said that, based on the feedback from the board, the water district will look to erect a fence around it. Board member David Johnson made the motion to require that installing a 6-foot-tall fence is a condition of approval, with Tom DePre seconding the motion.

Kennebec Water District supplies water from China Lake to about 9,000 residential and commercial customers in Waterville, Winslow, Fairfield, Benton and parts of Vassalboro, through about 172 miles of pipe. The town of Oakland also buys water wholesale from the district.