But it's right next to the Suisun Marsh -- a critical wetlands area.
The Suisun Marsh is an essential part of the San Francisco Bay and Delta eco-systems. It's one of the most important marshes on the West Coast - protected from development by state law.
Arthur Feinstein is former director of the Golden Gate Audubon Society. He is now volunteering with several environmental groups.
He says the Suisun Marsh is a critical stop for migrating birds, and much needed habitat for hundreds of other species.
"Mink, otter, tule elk, salmon, Delta smel, endangered species, several endangered species use the waters," said Feinstein.
But next door, just over the hills, is one of the biggest garbage dumps in Northern California.
The Potrero Hills Landfill is owned by Republic Services. It's been operating for 20 years, and is expected to fill up in another four.
"Should the landfill close up, it doesn't make the waste material go away. It just means it's got to go somewhere else," said Republic Services Area President Kevin Finn.
Republic has applied to almost quadruple the size of the landfill over the next 35 years. That's a volume roughly equivalent to 15,000 football fields - each stacked three feet high with garbage.
The expansion would be in a valley next to the existing landfill. General Manager Jim Dunbar thinks it's a perfect solution.
"It's an enclosed canyon valley. So there is very little impact from outside, water sources, outside people, it's all kept within one area," said Dunbar.
But environmentalists are outraged. They say the nearby marsh is so critical, such a massive expansion and change in the habitat is just too great a risk.
"What we have right now is a 900-acre valley and they are proposing to fill another 200 acres of it, and they are not only filling the valley, they are creating a mountain itself over 300-feet high," said Feinstein.
Feinstein says the valley that will disappear is important to the health of Suisun Marsh. It's dry during much of the year. But in the rainy season, the headwaters of a creek form here and drain into the marsh.
He says the expansion would endanger that.
"The headwaters are critically important for removing pollutants, for providing habitats for invertebrates and other critters. Headwaters are actually one of the most important components of streams," said Feinstein.
The landfill's owners insist they can engineer around any environmental concerns.
"Before we do anything on the property we analyze the grasses, trees, what kind of animals and wildlife, what kind of protection we need for them," said Finn.
But at least one Solano County supervisor is not convinced.
"The Suisun Marsh is such a special place that's of national significance. And to cut stumble take 260 acres of pristine land, move creeks, destroy vernal pools with the idea you can move them is just -- bottom line it's wrong," said Solano County Supervisor Barbara Kondylis.
Landfill officials showed ABC7 News the type of environmental precautions they take.
"That white slope there is part of the liner system. That is a very heavy, high density plastic line, chemical resistant, approved by the agencies, and on top of that we put another protection layer of soil and the trash goes on top of that," said Dunbar.
Solano County supervisors already voted three to two in favor of the expansion. But landfill opponents have been in and out of court, arguing over an environmental impact report that still has not been finalized.
When it is, the supervisors will vote again, and it could still go either way.
"I think it's the worst idea ever thought of," said Kondaylis.
"You look at all the technology that has gone into that landfill, I think they've been very responsible and very protective of the environment," said Solano County Supervisor Jim Spering.
The reason Potrero Hills landfill is filling up so fast is that it's become a regional landfill. Nearly 85 percent of the garbage comes from outside Solano County.
That's in direct violation of a law Solano County voters put into place years ago, but the county has never enforced it.
Written and produced by Jennifer Olney.
