WATERVILLE — Sixty-eight apartments could be built in the former Seton Hospital off Chase Avenue in 2023 if all goes according to plans by Waterville Redevelopment Company III LLC.

The Planning Board on Monday night voted 5-0 to approve the plan, which calls for 55 one-bedroom and 13 two-bedroom units that would be workforce housing and rented out according to tenant income, according to developer Kevin Mattson.

“If we are able to make our application to Maine State Housing within 60 days, we think by the end of the year we should be able to get through this process,” Mattson said.

Construction is expected to take 14 to 16 months, he said.

In 2013, Mattson bought the 150,000-square-foot Seton building, which in 1997 had become part of MaineGeneral Medical Center. The Planning Board unanimously approved the project in 2016 and again in 2018, when the number of apartments proposed was increased from 55 to 68, Planning Board member Bruce White noted Monday.

“Everybody I’ve talked to is anxious to see something happen, so I’m glad you’re coming back to us,” White said.

Changes in tax credit rules caused the delay in moving the project forward in 2018, according to Mattson, who said another change in January this year “completely changed the economics of this project again.” Because the previous plans expired, he needed to come back to the board for final approval.

The state has approved the building as a national historic landmark and construction must preserve the historic nature of the building. The 1960s-era building represents Miesian architecture, developed by Ludwig Mies van der Rohe, who founded the International Style of architecture, which features steel-framed and glass buildings.

The part of the building that would be commercial is on the first floor and in back of the building, though Mattson said he does not have immediate plans for the commercial and and storage part of the structure.

Resident Cindy Jacobs said she lives near the site and walks her dog there. She said motorists cut through the former Seton property via a road that extends from Lincoln Street to First Rangeway and she asked if it is public road. Drivers “fly through there,” she said.

Mattson said it is not a public road. He and Steve Roberge, a site engineer from SJR Engineering Inc. of Monmouth who prepared plans for the project, discussed pursuing ways to remedy the situation, including installing signs or putting in a concrete barrier.

Board Chairman Samantha Burdick noted that most of the apartments would be one-bedroom, and it is difficult right now to find larger housing for families in Waterville.

“I’d just love to see more of a variety,” she said. “I don’t know if it’s possible in this situation.”

Mattson said his company did a market study and the mix of one and two-bedroom units was based on that study. He said the mix could change.

Burdick, White, and board members April Chiriboga, David Johnson and Tom DePre voted to approve the project. Members Hilary Koch and Uria Pelletier were absent from the meeting.

In a separate matter, Waterville Redevelopment Company IV LLC, also a Mattson company, presented an informal preapplication  for a proposed 14-unit subdivision off Doctor’s Office Drive, which is south of the Seton site off Lincoln Street. Chase Avenue runs into Lincoln. Doctor’s Office Drive connects Lincoln Street to Kennedy Memorial Drive, but there is no existing right-of-way to allow traffic to go through to Kennedy, according to Mattson.

“There’s no plan to use that to go through to Kennedy Memorial,” he said.

Mattson said the plans for the subdivision are conceptual at this point and he welcomes input. Significant wetlands on the site limit what can realistically be done on the property, he and Roberge said.

Mattson acknowledged there is a limited supply of single-family houses in Maine.

“I’ve never seen anything like this residential demand that exists throughout the state,” he said.

The downside of building houses now is that the cost is very expensive, according to Mattson.

Preliminary plans call for building houses that are 1,800 to 2,600-square feet in size on 14 half-acre lots, with public water, sewer and electricity all underground, he and Roberge said.

Jacobs asked what the houses would sell for, with Mattson responding he’d like to sell them for $375,000 to $425,00. The same houses in Saco or Biddeford would be $675,000, he said.

“The most important thing is that there’s a market and people would buy those,” he said.

Johnson said he understands the demand for the houses Mattson is proposing to build.

“I think it’s a great price range for new homes in that area of Waterville,” he said.

Mattson said he expected to return to the board in May or June with more detailed plans. No vote by the board was required for the preapplication review Monday.

Mattson several years ago bought the former MaineGeneral hospital on East Chestnut Street in Augusta for $25 million and turned it into offices.