Two weeks before Falls Township officials are set to decide if a chemical wastewater processing plant will be built a half-mile from the Delaware River, staunch opponents of the project showed up in droves Tuesday evening, book-ending more than four years of persistent protest.

For 45 minutes, one critic after another stepped to the lectern at the municipal complex to implore the supervisors to vote against the proposal, which would permit Israel-based Elcon Recycling to truck in chemical waste from other states and process it into coarse salt or sludge. This would happen in a sprawling facility on the polluted Keystone Port Industrial Complex in Fairless Hills.

Opponents have questioned Elcon’s truthfulness and fear an accident — a mistake at the plant, a crash involving a truck carrying hazardous materials, or otherwise — could prove catastrophic. They say the health of residents and the Delaware hangs in the balance, citing concerns over compromised air and water quality, as well as Elcon’s track record in compliance and safety.

“They have no record. Zero. They submitted permit documents to the state in Hebrew,” Russell Zerbo of the Philadelphia-based nonprofit Clean Air Council said of Elcon.

Other attendees at the meeting questioned who would claim responsibility for cleanup when — not if, they said — a spill happened. They listed more than a dozen towns that use water from the Delaware for drinking, cooking, and bathing.

“It’s scary. It really is,” said Morrisville resident Clay Aberts, 49, who passed out red and white anti-Elcon T-shirts before the meeting. “You get an overall feeling you’re not being told the whole truth.”

Immediately after the 45-minute public comment period ended Tuesday night, nearly all the attendees who showed up in opposition to Elcon rose at once. “No Elcon,” a voice rose loudly, and the mass of red and white headed for the exit.

“We need to heal the Earth, especially in Bucks County,” a dozen people chanted 15 minutes before the meeting started, standing outside the municipal complex. “Earth in Bucks County is out of balance.”

No one spoke in favor of the plan.

The board has scheduled to hear Elcon at 7 p.m. April 30 at Pennsbury High School West Campus in Fairless Hills, and vote afterward.

The supervisors must assess whether Elcon complies with development and zoning codes, said Chairman Robert J. Harvie.

The Pennsylvania Department of Environmental Protection is tasked with determining whether Elcon would be an adequate fit for the township. The DEP, Harvie said, is projected to release its decision in May. “We don’t have any idea what the DEP is going to do,” he said.