An application to expand an existing biological research firm in a residential area near Wolf Trap Park and a proposal to build a 360-unit elderly housing project next to it are causing major problems for one another. At the same time, both proposals are generating strong opposition from homeowners in the Route 7 corridor west of Tysons Corner.

Hazelton Laboratories Corp. wants to expand its present facility on 47 acres at Route 7 and Towlston Road. But Hazelton leases the land from The Karloid Corp. That firm is currently trying to sell an adjacent 79 acres to Adult Communities Total Services Inc. (ACTS) for construction of a major life care facility for the facility. That 79 acres is the buffer required by Fairfax County to separate the existing laboratory facility from residential neighborhoods.

Neither company said it is trying to undercut the other but the dialogue over the two proposed projects is confusing both to McLean/Tysons area civic leaders and to those who make major land use decisions for Fairfax County. Lawyers representing both companies shared a platform in west McLean this week but both refrained from commenting on the plans supported by the other.

ACTS and Hazelton are both asking Fairfax to change the county's comprehensive land use plan so each can proceed with its project.

Residents of the area have said in several community meetings that construction of the elderly housing facility would destroy the buffer between the commercial lab and homes.

The ACTS proposal submitted to the county officials says a life care facility for the elderly "would provide an appropriate transitional use between the commercial use of Hazelton laboratory and the single-family dwellings to the north and east."

Hazelton has a long-term lease on the 47 acres now occupied by a series of buildings that are used for various research purposes. Hazelton, a major international biological and genetic engineering operation which uses animals in its testing programs, has been operating on the site under a special use permit since 1951, according to attorney Richard R. G. Hobson, a former Virginia legislator who is representing the lab.

Hobson said Hazelton's lease includes an option to buy the site.

Representatives of ACTS had declined to make presentations to the McLean Citizens Association's planning and zoning committee and other public meetings focusing on many land use changes proposed in Northern Fairfax. This week, attorney Ken Sanders revealed the details of the ACTS' plan to members of the Dranesville task force, a citizens study group appointed by Fairfax Supervisor Nancy Falck to study proposed changes and make recommendations to the county planning commission.

The proposed elderly care facility would sit on land which wraps around the Hazelton lab's site and have frontage on both Route 7 and Towlston Road. The site is just north of Wolf Trap Park.

ACTS, according to Sanders, has asked Fairfax to change its land use plan from a residential, one unit per acre, status to a low rise residential use to enable ACTS, a Pennsylvania-based company, to build 360 residential units including studio, two and three bedroomed apartments.

The complex would include a full service cafeteria, a 60-bed state-licensed nursing home and a 40-bed unit for those needing assistance but "not full care," Sanders expained.

"Entrance fees would be approximately $50,000 for the studios" and up to $150,000 for the three-bedroom units, Sanders said. "These buildings are low rise, 40 feet tall, residential," Sanders said.

Jinks Middleton, a task force member and a resident of the nearby Rocky Run community asked Sanders, "What will the impact on Hazelton be?"

"We think this solves the problem," by putting the elderly housing between the lab and the single family homes, Sanders said.

Steve Lopez, a Fairfax planning staff member, said the site where ACTS wants to build is a buffer in its present state.

"Part of the special permit for Hazelton indicated there would be 'no development' on the 79 acres. This is in our special permit files," Lopez said.

Hazelton's attorney Hobson said the company wants to make its international headquarters at the Route 7 site where the lab began operations more than 30 years ago. With operations in Germany and England, the company has $70 million in annual revenues employing 1,600 people with 400 working at the Route 7 site, Hobson said.

He said the company paid Fairfax $232,000 in taxes last year. "This is the high tech type industry like those Fairfax goes around the country trying to attract. Hazeton wants to put its headquarters on this site."

Both the Hazelton and ACTS proposals were filed in mid-December before the deadline for amendments to be considered this year during the annual land plan review. Hobson however said he has no specific language changes yet to present. "We will take language changes to nearby residents in early April," he said.

Stephen Hubbard, chairman of the McLean Citizens Association's planning and zoning committee, said the McLean group objects to both the Hazelton proposal and the ACTS plan. The group supports maintaining the existing residential land use on both sites.