A planned 157-unit fully affordable housing complex had its first of many public meetings at Valencia Gardens on Wednesday night and a Mission resident had virtually one concern: the prospect of increased sewage resulting in more flooding to Folsom Street.

“This is gonna dump into the sewer system that’s been dumped onto Folsom Street, correct?” asked Michael Crahan in the first comment of the night.

Flooding on Folsom is a perennial problem stemming from the capacity of the city’s pipes, and Crahan wondered whether the project had been through an environmental review and taken its sewage output into account.

Sam Moss, the executive director of Mission Housing Development Corporation, one of the two non-profits behind the project, told Crahan such issues would be looked at, but Crahan replied that the housing boom is straining city infrastructure.

“Sewage dumps onto Folsom Street, and no one’s been doing anything for a long time,” he said. “They keep building and it keeps getting worse.”

It was an isolated comment in a meeting otherwise concerned with amenities in the new development. The 157-unit project coming to 1950 Mission St. — between 15th and 16th — was awarded to the non-profit pair Mission Housing and Bridge Housing in July 2015 and will cost some $80 million to construct. Around $30 million of that is in city funds.

The project is scheduled to break ground by the end of 2017 and will take in its first residents in five years.

The development is split into two buildings — one of which is four stories tall, the other eight — with a courtyard planned for the space between and public alleyways abutting the building that connect Mission Street to Weise Alley.

Preliminary plans of the 1950 Mission St. project.

Preliminary plans for the 1950 Mission St. project.

Preliminary plans of the 1950 Mission St. project.

Preliminary plans for the 1950 Mission St. project.

The complex will mostly house families making between 45 and 60 percent of area median income — between $41,300 and $55,000 for a family of three — in a mix of units from studios to three-bedrooms.

The studios, Moss explained, are meant to keep people in the building after their families have left, since many affordable housing complexes house individuals in two- or three-bedroom units when they could be in smaller spaces.

A fifth of the units will be reserved for formerly homeless families chosen through a program of the Human Services Agency and will have a lower income cutoff.

The housing project replaces the Navigation Center currently on the spot, which serves as a transitional center that can take in entire homeless encampments — pets and all — at once.

Christina Olague, a former planning commissioner, brought up the closure of the center and wanted to know what would happen to the dozens of homeless people who stay there at any one time.

“Where will the Navigation Center be relocated?” she asked.

The non-profit developers are not responsible for that decision, but Sam Dodge, the mayor’s point-person on homelessness, said in a phone call before the meeting that sites city-wide were being explored.

“We’re actively working on a lot of different sites,” he said, mentioning that Districts 5 and 10 could particularly use new centers. But the center on Mission Street won’t be relocated per se. It will be a year before it shutters, and Dodge hopes to have two others up and running by then.

“My hope is that we can be operating two at a time,” he said. “I would open up a third and we could then close the Mission [center] and operate with two.”

At the Wednesday meeting, groups split up and sat around posters of possible amenities for the project, placing little green stickers next to the features they would want in the new building — like bicycle pathways and a community garden — and red ones next to those they wouldn’t — like a facade similar to that at Vida Apartments.

“Close your eyes,” said Oscar Grande from the non-profit Poder while leading a Spanish-speaking group. “I want you to imagine what we can do in this space,” he said, speaking of the courtyard between the buildings.

The group talked murals, opportunities for local artists, and cultural activities. Juan-Jose Carrizalas, who lives in Valencia Gardens, suggested an exterior notice board so residents could put up flyers about events in the neighborhood.

“Like a bulletin mural,” said Brenda Morales, a Mission District resident, while rocking her newborn.

Others later suggested tai-chi classes, zumba and dancing, saying adults need to keep occupied while their children play in the park.

“Also a place to get massages,” said Andres Hernandez, a Mission District resident.

“Put it up,” said Grande to a note taker. “Put a little star next to that one.”

The joins three other fully-affordable developments — at 490 South Van Ness, 2070 Folsom, and 1296 Shotwell — that will bring some 430 units to the Mission District in the next half-decade. It’s also the first ground-up construction for embattled Mission Housing in 15 years after the non-profit saw its city funding slashed more than a decade ago.

“This is really awesome,” Moss said. “It means a lot that Mission Housing has finally gotten to the point where we’re planning for the next five years instead of worried about the past five.”