Caltech wants to build a new facility on one of its rarely used parking lots on the corner of Green Street and Holliston Avenue.
The parking lot is steps away from St. Philip the Apostle Church.
"Our [transitional kindergarten] classroom is 88 feet away from the edge of this parking lot, so you start from the beginning from the building of itself ... it's going to be a 93,000 square-foot building," said Christina Blacker, a parent at the school. "The noise ... the dust from a safety and health perspective for the kids."
Caltech, in partnership with the Trammell Crow Company, wants to develop the lot into a research facility.
"We see this as an additive opportunity to take what is currently an underdeveloped, underutilized parking lot, and to bring another layer of vitality and opportunity," said Shayna Chabner McKinney, the Chief Communications and External Relations Officer at Caltech.
St. Philip sent an email to the community listing concerns about the project, which include security and traffic hazards.
School officials are also asking parents and churchgoers to voice their concerns, saying in part, "Between the size, safety concerns, and lack of environmental review, we are not comfortable with this build."
"There's so much uncertainty right now as to what will be in this structure and who will be occupying it," said Blacker. "All of those concerns are on the table: the concern for safety, the concern for the structure and building itself."
Chabner McKinney said Caltech is mindful of the community's concerns, saying they want to work with their partners and neighbors.
"We've met with the school leadership, we've met with other neighbors on the innovation corridor, the Green Street commercial center, and we'd love to continue that conversation and discussion," she said.
The city of Pasadena released a statement, saying in part, "New structures have been built on the St. Philip site within the last 5 to 10 years, and that is allowed as is construction on adjacent sites. If any of the adjacent church or school buildings are eligible for historic designation, the proposed project would not impact the ability to designate those structures."
The city also said the project is still in the design review phase and will go before the design commission in November.