Sequoia Building Corp. has unveiled its plans for Cascades, its 1,178-acre recreational community on the banks of the Potomac River in Loudoun County.

But before construction starts, county supervisors must approve a proposed change in the mix of housing, and the company must allay some citizens' concerns about roads leading to the development.

Sequoia President Ray Smith said that he plans to take advantage of the site's commanding views of a two-mile-wide expanse of the Potomac River when he constructs up to 2,052 homes and a marina.

Sequoia filed an amended conceptual development plan for Cascades in August that proposes keeping the total of 2,052 units approved in a 1979 rezoning of the property, but increasing the number of town houses and condominium units at the expense of single-family homes.

To date, citizens have raised no objection to the proposed change in housing mix, according to Loudoun County planners.

The only complaint about the project from Loudoun citizens so far concerns the location of a neighborhood shopping center, said County Zoning Administrator Timothy J. Krawczel.

Residents of the Great Falls Forest neighborhood subdivision said in a meeting with county planners that they are concerned about placing stores adjacent to their homes instead of in the center of Cascades property, as originally proposed, Krawczel said.

County staff comments are due by Oct. 15, and the board of supervisors is scheduled to act in November.

Citizens in Fairfax County, however, have voiced a separate concern about the project. In meetings with county officials and at hearings over the past five years, different groups of Great Falls residents have said they fear the two possible access routes to the Loudoun property would disturb their tranquility.

Sequoia is promising to spend $3 million to construct a road from its property line south to join Route 7. The road would run through the Holly Knoll subdivision, and residents there want berms and landscaping included to reduce traffic noise.

Sequoia's engineer, Roland de Polo, said he is willing to provide this buffer.

"We want to do whatever we can to be good neighbors," he said. But the Virginia Department of Highways and Transportation must approve making room for the landscaping by eliminating the median strip on the portion of the highway passing through Holly Knoll. And, so far, the highway department has not been sympathetic, De Polo said. Highway department officials could not be reached for comment.

The 2 1/2-mile section of the road that Sequoia would build from Cascades is part of the planned Algonkian Parkway, which will swing through residential developments in Loudoun County north of Route 7, and extend east from Route 28 to rejoin Route 7 at the proposed Springfield Bypass in Fairfax County.

Sequoia plans to have its section of the parkway ready by the time it sells the first units at Cascades. If negotiations with the highway department and property owners over whose land the roads must cross fail, however, another group of Great Falls residents could bear the traffic burden.

Sequoia can build up to 1,700 homes using the country byways of Brockman Lane and Seneca Road in Fairfax County to reach Route 7, Smith said.

One person fighting that route is the Fairfax County supervisor for the area, Nancy K. Falck. The roads in question were designed for farm vehicles and cannot handle the traffic that Cascades would generate, she said.

Whatever the outcome of the road problem, one advantage of the proposed change in housing mix is that it would generate less traffic.

The conceptual development plan amendment proposes 861 single-family homes, down from the 1,230 originally proposed; 677 town houses, up from 533, and 513 condominium units, up from 287.

Planners say that town houses and condos generally mean fewer cars and fewer schoolchildren than single-family homes.

This change in mix of housing also would leave more of the Cascades property undisturbed, so that larger stands of trees and open spaces can separate the 18 proposed villages, said David Cobey, the project's architect. Cobey works for the Burkes Group, which has won national awards for its design and locally is known for The Residences at Georgetown Park.

Members of the Loudoun County planning staff could not comment on the proposed changes because no one has reviewed the plan amendment.

The conceptual development plan that Sequoia wants to amend is a legally binding document that indicates the general location and number of homes, roads, stores and recreational facilities.

Sequoia is aiming for the up-market customer, buyers of a second home or parents whose children have left home and who are seeking a smaller but prestigious house, Cobey said. Prices will range from $110,000 to $350,000.

Plans show a central clubhouse on the lot overlooking the Potomac River. The facility will be equipped with a swimming pool, weight room, whirlpool and tennis courts. On the waterfront, 24 acres is zoned commercial, which Smith said could include some shops and restaurants. Scattered elsewhere on the site will be lakes, two more swimming pools and jogging trails.