A rendering shows a proposed new mixed-use building at 73 River St. in Mattapan. Image courtesy BRA/Nunes Trabucco ArchitectsA landowner who hopes to build a new, four-story mixed-use building on River Street in Mattapan will undergo a city review process next year for the project, which would include 18 two-bedroom units of housing above a ground floor retail space. The proponent, George Tsolirides, and his architect appeared before the Apple Grove Civic Association last week to discuss his plan, which would replace two one-story commercial buildings now on the site with one larger building encompassing nearly 34,000 square feet on three parcels that Tsolirides owns at 73 River St. The developer originally proposed a total of 21 two-bedroom units, but has scaled back the residential component to 18 units after meetings with abutters and civic leaders. The site, which borders Sturbridge Street, is now home to a dry cleaners and the River Street Grille, a restaurant. “The proposed project will result in revitalizing the appeal and vibrancy of the River Street streetscape,” the proponents wrote in a letter of intent form filed with the Boston Redevelopment Authority last June. “In particular, the project will remove non-descriptive, underused brick structures”… and replace them with “an aesthetically pleasing residential facility complementing the immediate neighborhood.” The project will require variances from the city’s zoning board, since it is situated in a district currently zoned for a two-family, two-and-a-half story building. It will also be subject to the BRA’s small project review process, known as Article 80. In a letter sent to BRA director Brian Golden last summer, the architect Lucio Trabucco, who is named as a “partner” in the project, said the proponent had initially discussed building on the site in 2011. “Since this time, [Tsolirides] has engaged in extensive discussions with staff at the BRA concerning project design, conducted outreach with local elected and appointed official [sic], and made presentations to the abutters and the local neighborhood organization.” Nick Martin, a spokesman for the BRA, said that the authority was working to arrange a meeting with the developers and the BRA’s urban design team. Myrtle Huggins, who leads the Apple Grove association, said that neighbors who abut the proposed building site are “very concerned” because, she said, they “had no knowledge about what’s going on.” Most civic members, she said, were opposed to the plan as it stands now due to a lack of outreach. “I think a little more work has to be done,” she said.