At a meeting next Tuesday, members of a citizens committee will have their say.

The county officials, members of a project review group who represent both County Councils, were asked to look at proposals for the pipe after community members were overwhelmed by the technicality of the project at a meeting in May.

The project review group recommended that WSSC build the water main close to Interstate 270 and the Capital Beltway, a route that, for the most part, will keep construction away from residences.

The recommendation marks the steady progress of the Clean Water Connection, a water main that will connect the Potomac Water Filtration Plant in Potomac with existing pipes in Kensington. The new main is needed because of increasing demand in Prince George's County and the eastern part of Montgomery County.

The recommendation that county officials made for the path of the pipe is south from its origin at the intersection of Tuckerman Lane and I-270. It will stay close to I-270 and I-495 until it ties into existing pipes near the Mormon Temple on Stoneybrook Drive in Kensington. The pipe's construction will affect many communities in the downcounty, including Bethesda, Kensington and Garrett Park.

It will be constructed 150 to 300 feet underground, with all construction taking place through four shafts located along the length of the project.

The next meeting of the Citizens Advisory Committee -- a group of interested residents and representatives from civic associations -- being held at 7 p.m. Tuesday at Grace Episcopal Day School in Kensington, will give the committee a chance to learn about the proposed alignment and make suggestions.

"We'll present [the plan] ...and go over with the CAC all of the reasons why we think this one is the winner," said Project Manager John Mitchell of WSSC. "We'll ask [committee members] for feedback if they see flaws in our reasoning or issues that need to be addressed in the design phase."

One of the larger issues of contention is likely to be the location of the four shafts. The two endpoints of the pipe are fixed and will serve as retrieval shafts where workers will remove the machine that is used to dig the tunnel. Those shafts require about one acre and will be used periodically throughout the three-year construction. Another shaft, known as a riser shaft, will be located in Rock Creek Park at the intersection of Beach Drive and Rockville Pike. The 1/2-acre site will be used periodically to tie in the new water main with existing pipes.

But the largest of the four shaft sites is the working shaft. In the proposed plan, the two- to three-acre working shaft site sits north of the Connecticut Avenue cloverleaf at I-495. The working shaft will be the site of most of the construction associated with the project. From that site, the tunnel-boring machine will be lowered into a hole and it will dig in each direction. The site could be used 24 hours a day.

At the next meeting of the advisory committee, scheduled for Tuesday night, WSSC officials hope to hear from the community. If the committee approves the plans, they will be forwarded to the Montgomery and Prince George's county councils, which must also approve the route before construction can begin.

At a previous meeting, the committee narrowed the nine original options to three, discarding plans that called for laying the pipe in a trench dug by workers. Those plans would have called for cutting down trees and disrupting traffic along the length of the pipe's route.

"There are a lot of unknowns until you get a contractor on board," Mitchell said, listing scheduling questions and type of materials as just a few of the questions still unanswered.

For example, the contractor could decide that it would be easier to have sections of pipe delivered at a different location, which would mean delivery trucks might have to go through usually quiet neighborhoods.

"The more restrictions you put on a contractor, the more difficult it will get," Mitchell said.

Mitchell said WSSC hopes that once a final alignment is chosen, the advisory committee will rotate out people who do not live along the pipe's route, and then include people who will be affected by the construction.