LOS ANGELES -- The Boeing Co. has reached a tentative agreement with the state to clean up its contaminated nuclear testing facility in the hills above the San Fernando Valley and hand it over for use as parkland. The tentative pact, reached Friday, was negotiated by the governor's office, Boeing and state Sen. Sheila Kuehl, D-Los Angeles. It calls for Boeing to contribute $22.5 million over the next 30 years to pay for maintaining the property, which straddles the Los Angeles-Ventura County line in the hills above Simi Valley and the western San Fernando Valley. Boeing spokeswoman Blythe Jameson estimated it will take about 10 years to clean up all the pollution that decades of testing have left at the 2,850-acre Santa Susana field lab. Boeing owns about 2,400 acres of the site, and NASA owns the rest. The company said it will work with NASA to acquire the entire area, clean it up and hand it over to the state.