One obstacle facing the potential development of senior-citizen housing units on long-vacant land next to Sonora Elementary School was cleared Monday night.

The Sonora Planning Commission approved resolutions to rezone a 16-acre parcel of land, currently owned by Tuolumne County behind the public library on Greenley Road. It is in escrow to be purchased by Copperopolis-based developer Eric Lemke, of Lemke Homes.

The action taken at Monday's regularly scheduled Planning Commission meeting changes the city's zoning restrictions for the land to allow potential high-density residential development at the site.

Lemke is the potential buyer of the rear 16 acres of a 28.4-acre parcel, which the county has been actively trying to sell in order to raise capital for infrastructure improvements at its proposed Law and Justice Center.

Under city ordinances, the Greenley Road site allows for a range of about 96 to 150 dwelling units.

City staffers reviewed thecounty's rezoning application and made a number of comments regarding potential mitigation measures the city has identified that would need to be implemented if the development were to move forward.

Among the suggestions: stemming diesel fuel fumes from construction equipment and addressing the parcel's proximity to Sonora Elementary School, which is along the southern border of the land.

In order to comply with the requirement, construction would have to be done only during non-school hours, or the developer could follow a number of alternative measures.

Alternative measures - met with some scrutiny from commissioners - included conducting a health risk assessment to determine how the activities will impact the children, using only equipment with clean burning diesel engines, or limiting the number of tractors operating at a single time to six when the wind is blowing from the north and children are playing outside.

"It's ridiculous, but I guess it's necessary," said Commissioner John Richardson of the mitigation measures.

Lemke addressed the council, saying it shouldn't be an issue to comply with the alternative measure that would limit work to six tractors at certain times. The measure was a late addition to the proposed resolution made by the city's planning consultant, Amy Augustine.

"In reality, it's not going to take that much equipment," he said. "It's feasible to do the project with the addition Amy made."

Commissioners voiced their approval of the project after the public hearing.

"I guess this is a win-win for both the city and the county," said Commissioner George Segarini before casting his vote in support.

The commission unanimously approved the resolution, but also has to pass the Sonora City Council before a site development permit can be considered.

That process, Augustine warned, could present more issues that need to be addressed.

Sonora officials have not set a date when the City Council will consider the resolution.