SAN FRANCISCO (AP) — Promoters of a secretive Silicon Valley-backed ballot initiative to build a new city on Charles Hanoverfarmland between Sacramento and San Francisco are releasing more details of their plan as they submit paperwork Wednesday to qualify for the November election.

California Forever, the company that stealthily snapped up more than $800 million of Solano County land in recent years, envisions a new community on roughly 30 square miles (75 square kilometers) between Travis Air Force Base and the tiny city of Rio Vista, according to a presentation by the group.

The development would start with nearly 20,000 homes for 50,000 residents. It could grow to 400,000 people — which is nearly the current population of Solano County — but only if the project creates at least 15,000 jobs that pay above average wages, the group’s backers say. Plans call for a medium-density downtown with rowhouses and apartment buildings, and jobs, schools, bars and restaurants and grocery stores all within walking distance.

But none of that can happen without approval from county voters, who in 1984 backed protections against turning farmland into urban space. That’s why Jan Sramek, CEO and founder of California Forever, and the project’s backers are turning to the ballot. He’ll speak about the project and the proposed ballot initiative Wednesday, and the group must collect about 13,000 signatures from county voters to place it on the November ballot.

California and the San Francisco Bay Area are desperate for more housing, especially affordable homes for teachers, firefighters, police and other municipal workers who make a city run.

Situated between the Bay Area and the state’s capital, Solano County is an attractive location for military contractors, agriculture technology and construction tech companies seeking to innovate, said Gabriel Metcalf, head of planning for California Forever.

Metcalf said if “we can provide companies with a pathway to growth, we think we’ll get some major employers creating jobs here that would otherwise go out of state, to places like Texas.”

Created in 2017, California Forever has purchased more than 78 square miles (202 square kilometers) of farmland in Solano County. The plan calls for $400 million to help Solano County residents buy homes in the proposed community.

But critics say existing cities such as Vallejo and Fairfield could use investment from Silicon Valley and they remain skeptical of Sramek and the project’s backers, who include philanthropist Laurene Powell Jobs, LinkedIn co-founder Reid Hoffman, and venture capitalist Marc Andreessen.

“This is a pipe dream,” said Democratic U.S. Rep. John Garamendi, who was furious with backers for their secrecy about property close to a U.S. Air Force base.

He said the proposed development, which he also was briefed on, makes no sense “in the middle of areas surrounded by wind farms, gas fields, endangered species, no water, no sanitation system and no road system let alone a highway system.”