A land use battle over a proposed 400-home development in East Orange heated up Monday night, with many residents airing concerns about threats from flooding, fires and methane gas from an adjacent landfill.

“This Planing Commission will see this land flood in your lifetime,” resident Bob Kirkeby told a packed Orange Planning Commission hearing where more than 40 people spoke.

He’s seen “moving water through that whole property” in past floods, Kirkeby added.

The proposed Rio Santiago project along Santiago Creek would convert a former sand and gravel mine into a 395-home development, of which two-thirds would be for seniors.

Its developers, Milan Capital Management and JMI Real Estate, argued that the project would enhance the area by using aesthetically pleasing buildings and setting aside most of the land for open space, recreation facilities and trails.

The vision is “to convert an active existing sand and gravel operation … to a beautiful, recreational, open-space community,” said Ken Ryan, a principal with the developer’s planning firm, KTGY.

Planners focused on creating trails, parks and protected open space that highlights the underlying beauty of the land, he added.

A majority of public comments opposed the project.

Kathy Ashford, who lives next to the creek, said she was concerned about evacuating hundreds of people in the event of a fire.

“There is one way in and one way out of this whole development,” she said.

As the comments stretched into the night, an unexpected twist appeared.

To bolster their case for housing, the developer had been claiming that the site is still a mining operation, which could continue for another 40 years if the homes aren’t approved.

A recent mailer for the project calls the land “the Sully-Miller mine” and an “active Sully-Miller mine/dump site.”

But an executive with Sully-Miller told commissioners that’s totally false.

“Sully-Miller stopped mining aggregates two decades ago,” said Scott Bottomley, a vice president with Sully-Miller Contracting Co. “Sully-Miller never operated a dump at this site.”

Any expansion, he added, “has been done by the current property owner … by his hand, at his direction.”

The new owner “continues to drag our name through the current activities,” Bottomley said, adding that he opposes the project and its developer’s tactics.

As for the methane gas, the project’s official environmental report states the soil contains enough methane to leak into the proposed senior housing and cause an explosion.

“The possibility exists that this methane could infiltrate buildings in Planning Area C and concentrate in rooms with limited air exchanges,” the report states. “The methane concentration could exceed its lower explosive limit (5% by volume), creating a potentially explosive mixture.”

To prevent this, the report calls for the installation of vapor barriers or venting systems beneath buildings.

The developers, meanwhile, told the commission that they’ll be placing methane monitors in the area.

Representatives of the local YMCA and Mabury Ranch Homeowners Association, meanwhile, said their boards support the project.

And John Moore of the Santiago Creek Greenway Alliance said the project “provides the best realizable deal we’re going to get” to preserve open space.

Local activist Shirley Grindle agreed.

“No one has stepped forward to buy this property” to make it fully open space, she said.

Many opponents also pointed to the Santiago Creek Greenbelt Plan, a city-approved 1970s vision for preserving natural open space along the creek, which feeds into the Santa Ana River.

“People were clear 40 years ago. They wanted open space,” said resident Katrina Kirkeby, adding that the recent referendum against another development sends the same signal.

“The public has been very clear. Do not rezone properties that have been designated open space.”

Others said the developer should simply build homes on the small portion of land that’s zoned residential.

Milan “bought it on the gamble that they could get the zoning changed and ignore the hazards,” said resident Jane Canseco.

“It’s not up to the government to fulfill their magical thinking and bail them out.”

Local activist Theresa Sears agreed, calling the proposal “nothing more than a bail out” for the developer.

As for the greenbelt plan itself, city staff acknowledged on Monday that the project’s environmental report incorrectly states that it and other plans were never approved by the city.

Housing proposals for the property have been around for more than a decade.

An earlier proposal, known as Fieldstone, called for less than half the number of homes but was ultimately rejected by the City Council in 2003 after opponents collected enough signatures for a ballot initiative.

Commissioners set an 11 p.m. cutoff for the meeting and are set to pick up where they left off on Jan. 27. Several speakers chose to hold their comments until then.

However the commission ends up voting, the project’s fate will ultimately be decided by the City Council.

You can reach Nick Gerda at ngerda@gmail.com, and follow him on Twitter: @nicholasgerda.

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