Fairfax County officials expect little opposition at a public hearing July 29 when they are scheduled to vote on the largest road bond program ever offered residents.

The proposed $134.4 million bond referendum includes more than $90 million toward construction of two segments of the Springfield Bypass, a 35-mile cross-county highway that would provide easy north-south access through the county. County officials hope to add another $45 million to the package to upgrade and widen 12 major roadways and intersections.

So far, opposition to the bond package is slight. Several citizen groups said it was too soon to plan any action on the referendum.

"It's a foregone conclusion that it will be on the ballot," said Robert H. Thornton, cochairman of the Mount Vernon Council of Citizens Associations. "It would be academic to start discussing it this early."

Supervisor Nancy K. Falck (R-Dranesville) said she has not heard anything from the civic associations in her district. "I think most of them are not yet aware of it," she said.

The exception is the proposed 4.1-mile South Van Dorn Street extension that will cross the 1,262-acre Huntley Meadows Park, the county's largest wetland and wildlife preserve.

An environmental group, the Citizens Alliance to Save Huntley, has mounted a vigorous offensive to fight the proposed four-lane highway that would link South Van Dorn Street to Rte. 1 in the Hybla Valley region. Norma Hoffman, president of the 300-member group, said the road would destroy Huntley Meadows' natural environment and harm animals living there.

"We have scientific data to prove that there will be enormous damage to vegetation and wildlife there if the highway is built," said Hoffman.

Hoffman has enlisted the support of several national environmental groups, such as the Northern Virginia Sierra Club and the Audubon Naturalist Society of the Central Atlantic States Inc., plus government scientists and geologists to help her organization block plans for the highway.

Supervisor Joseph Alexander (D-Lee) said the $13.2 million extension is designed to get traffic off residential streets and onto the highway.

" The Lockheed extension is the only north-south access we can get. All of our traffic right now goes through the residential streets," Alexander said.

He said Hoffman's group was "well meaning" but the extension "does not go through any sacred areas of the park."

Board Chairman John F. Herrity said the county government "is trying to be sensitive to the needs and concerns of the people living near the construction and who will be bearing the brunt of these improvements."

Four of the dozen planned road projects have not reached the design stage. County planners must purchase the land on another four projects before improvements can begin. Although the bond referendum is aimed to allow officials to fund the proposed street projects, the county is not legally bound to adhere to its original construction plan.

The 12 road improvement projects slated for future construction are:

*Extending South Van Dorn Street to Lockheed Boulevard and Rte. 1.

*Widening Blake Lane to four lanes from Jermantown Road to Rte. 50 at Pickett Road in Fairfax City.

*Widening Telegraph Road to six lanes from Franconia Road to I-95.

*Widening Rolling Road to four lanes from north of the Southern Railroad to Burke Lake Road.

*Widening South Van Dorn Street to six lanes from Franconia Road to I-95.

*Moving the intersection of Rte. 123 at Old Dominion Drive and improving Rte. 309 from Rte. 123 to Chain Bridge Road.

*Widening South George Mason Drive from Rte. 7 to Arlington County line.

*Improving the intersection of Rte. 50 and Graham Road.

*Widening John Marr Drive to four lanes from Dawson Street to Old Courthouse Road.

*Improving the intersection at Franconia Road and Commerce Street.

*Improving the intersection at Rte. 7 and Baron Cameron Avenue.

The two Springfield Bypass segments to be constructed from bond referendum funds will run from the Dulles Toll Road to Rte. 50 and from Rolling Road across I-95 to Beulah Street. The county's public hearing for the proposed bond is scheduled for July 29 at 7:30 p.m. in the Massey Building, Fairfax City.