A Woodbridge-based nonprofit group has come up with a $941,000 plan to restore historic Rockledge Mansion, two years after it was gutted by fire.

The Historic Preservation Society Ltd. of Woodbridge has submitted to the Virginia Historical Society and the town of Occoquan a three-phase proposal to renovate Rockledge. The proposed restoration effort would take 18 months to complete, if an initial $49,500 phase-one study showed that the mansion could be saved.

"Somebody has to save that house," said John Amatetti, a partner in the society. "I'm not a millionaire, just a guy who wants to save a place that reminds me of my mother and father's home in central Italy."

The once-stately mansion was gutted by an arson-caused fire in 1980, after owner Donald Sonner had spent six years restoring it. In February, Sonner mounted a drive to obtain $1.1 million in state aid to restore the mansion, built in the 1750s on a three-acre site overlooking the Occoquan River.

"What we need now is funding from the state or federal government so we can move ahead with phase one," Amatetti said. "We've spent nine months working up this proposal and gotten the endorsement of the town, but now it's time to get moving. If the first phase shows it can be renovated, then we march. I'll go to the president if I have to before I'm through." Vienna Set to Begin ---Work on Next Budget --

The Vienna Town Council begins marking up Town Manager Brackenridge H. Bentley's proposed $7.4 million budget for the coming fiscal year when it meets on Saturday.

Bentley is urging the council to hold the line on the property tax rate and increase spending by nearly 12 percent in fiscal 1983. Vienna homeowners would continue paying 33 cents per $100 of assessed property value under Bentley's fiscal plan.

"Despite the fact that you hear stories of gloom about the real estate market bottoming out, the assessor doesn't feel that way," Bentley said. "Assessments have increased by about 12 to 14 percent in the town. I wanted to lower the tax rate so that tax bills wouldn't be higher this coming year, but we just couldn't do it."

After informally looking over Bentley's spending package late last week, the Town Council planned to meet in a special public work session at 9:30 a.m. Saturday in the Town Hall council chambers. There will be public hearings on the budget May 17 and June 14, and the council is scheduled to adopt a final plan June 21.

"One of the most important aspects of the budget is replacing the town police radio system," Bentley said. "It's so dangerous now that some police officers can't communicate out on the road. The mobile radio units are 16 and 22 years old. In 1981, one of the mobile units was out of service 56 times, sometimes for several days."

Bentley estimates that it would cost $85,000 to overhaul Vienna's police radio system, adding 17 portable radio units, nine mobile units for cruisers and unmarked cars and a new base station.

In his budget package, Bentley also recommends hiking the resident water rate by 17 cents to 85 cents per thousand gallons and increasing nonresidents' water rates by 22 cents to $1.13 per thousand gallons. Sewer rates would climb by 28 cents to $1.90 per thousand gallons. In the last two years Vienna has lost nearly $305,000 operating water and sewer services in the town. --JANE SIMS PODESTA