Todd Stager of CEDG Engineers of Mechanicsburg, Pa., said Creek Farm Village would include two recreation centers, each with outdoor pools, along with other recreational areas and retail space.
"This is a community," Stager said. "It will have amenities in it that will keep people on site."
"We're talking a town almost the size of Greencastle" in population, Supervisor Curtis Myers said. Once fully developed, he said it could increase the township's population by almost 25 percent.
Supervisor Scott Diffenderfer said the sketch plan apparently showed some houses sited within the flood plain and Supervisor Robert Whitmore said a green space area along the creek "will be completely flooded in the springtime."
As the plan develops more fully, Stager said the locations of structures could be shifted out of flood plain areas.
Whitmore also questioned how much traffic the project would generate and how it would affect Castlegreen Drive to the north. He said residents would use Castlegreen Drive to avoid the intersection of Pa. 16 and U.S. 11 east of the development.
"Castlegreen Drive is not built to handle several thousand additional cars going through there each day," Whitmore said.
Craig Mellott of Traffic Planning and Design Inc. of Harrisburg, Pa., said the mixed-use development would generate less traffic than a comparable development of single-family dwellings. The Pennsylvania Department of Transportation also would require the developers to make road improvements to intersections away from the site and a traffic signal probably would be required at the entrance.
Stager said the development originally was conceived as a gated community, but whether Castlegreen Drive was a throughway from Pa. 16 to Williamson Road would be up to the supervisors.
Whitmore said he believed the project also would increase the student population of the Greencastle-Antrim School District.
"Could you set aside $20 million for the school district to build a new school?" he asked.
"Twenty million dollars is a lot of money for this size of development," Stager said. He said he could not speak on behalf of the developers on that issue.
The supervisors also raised questions about the effect of the project on water and sewer systems. Stager said there still were questions as to whether it would have its own sewer and water systems.
Township attorney John Lisko said he did not believe the developer had met all of the requirements needed to get conditional approval of the plan.