A former rocket engine and nuclear test site south of Simi Valley will be cleaned to the strictest federal standards possible, following a deal reached between state officials and community members that was announced Tuesday and hailed as historic.

In reaching the agreement, the state asked the U.S. Environmental Protection Agency to wait six months before deciding whether the Santa Susana Field Laboratory should be listed as a Superfund cleanup site. The agency has heeded the request.

"There is joy today in the long-suffering community surrounding this very contaminated site," Dan Hirsch, director of the nuclear watchdog group Committee to Bridge the Gap, said during a news conference. "Today an agreement has been reached with the Schwarzenegger administration, that the strictest cleanup standards, those contained in SB990, will remain in force."

Senate Bill 990, which became law Jan. 1, was introduced last year by state Sen. Sheila Kuehl, D-Santa Monica. It calls for the 2,850-acre site to be cleaned to the EPA's rural-residential standards before it is released for use.

In a move that stunned activists, Schwarzenegger signed the bill but announced an agreement with landowner Boeing Co., which called for the transfer of the land to the state for use as open space or parkland and may have allowed for the land to be cleaned to standards lower than those in SB990. Kuehl agreed to draft an amendment to her bill, which would have essentially gutted the standards it called for.

But on Tuesday, Linda Adams, the state secretary for Environmental Protection, wrote to Kuehl releasing her from her agreement and outlining the new arrangement born out of recent marathon meetings with community members.

"This is a big win," Kuehl said. "And a lot of kudos for Secretary Adams. (SB)990 stays in place. I was pretty surprised about this."

Working out a binding deal

Kuehl said the state should retain oversight of the cleanup at the field laboratory, which was the site of a partial nuclear meltdown in 1959. The state Department of Toxic Substances Control is well equipped to ensure the site is cleaned to a high standard, she said.

During the next six months, state officials will hammer out a binding, final agreement — with Boeing, which owns a majority of the field laboratory, and the National Aeronautics and Space Administration, which owns 450 acres — that is based on a letter of intent the parties signed in October.

At the same time, the state will consider the pros and cons of having the site listed as a Superfund site, which would make the EPA the lead agency overseeing all site cleanup. The six-month window also gives the state the opportunity to decide to support the listing.

Even if the state takes the lead, it is seeking the federal agency's support, according to a letter of intent among Adams, California Resources Agency Secretary Michael Chrisman and community members.

State officials say they would like the federal agency to take the lead role in a full radiological characterization survey of the site, which would be conducted with the U.S. Department of Energy. The DOE is in charge of the cleanup of radioactive contamination at the Field Lab.

The EPA has also been asked to provide technical assistance to DTSC and access to radiation experts.

"We think it's very important to partner with EPA, but at this point it is unlikely that we will find (Superfund listing) advantageous for the community," Adams said during the press conference.

Superfund official weighs in

But federal EPA officials are concerned about the state's desire to take the lead in the survey. Keith Takata, Superfund division director for the EPA's Pacific Southwest region, said in a statement that one of the reasons the agency sought Superfund status was to deal with the radiological portions of the site.

Without the listing, "we are uncertain about the authority and resources to do the work, but we will work with the state on finding the best way to meet its request," Takata wrote.

The EPA announced its interest in listing the Field Lab as a Superfund site in December and asked the governor to respond in 30 days. The administration asked for a delay, resulting in Tuesday's announcements.

The environmental agency had studied portions of the lab as a potential Superfund site twice before and failed to add it to the list. This time around, the EPA studied the entire site before making its decision.

Following the state's announcement Tuesday, a spokeswoman with Boeing said the news didn't change the company's commitment to thoroughly cleaning up the site.

Along with the support of environmental organizations, such as the National Resources Defense Council and the Sierra Club of California, which helped broker the new agreement, elected officials also supported the change.

Assemblyman Cameron Smyth, R-Santa Clarita, whose district includes Simi Valley — and who plans to carry legislation that would make the lab parkland after it's cleaned — said he will continue to work on the framework for the bill.

"The ultimate goal is to ensure the land is cleaned up to what will allow it to be used for public enjoyment," he said.