Peter Halliday accused the councillors who prompted a scrutiny meeting next Tuesday about the Holland Haven-to-Clacton defences of "scaremongering".
Councillor Pierre Oxley, who called in the meeting, said Mr Halliday's accusation was "garbage".
"We're not against the project because we want it to happen," he said.
Mr Oxley claimed the council had been unclear about how much of the beach would be sand, and how much would be shingle.
"We want to know what the mix is," he said.
"Residents are saying they want to be able to lay on the beach and play on it, but if it's all stone or shingle that will be an issue."
The Conservative-run council last week submitted its application to the Environment Agency, which it hopes will contribute £22m towards the project.
If successful, 25 groynes will be installed and the beach will be recharged.
Mr Oxley said the council could have avoided the scrutiny meeting if they had "put all the percentages in the report".
Mr Halliday said: "We have been completely open and transparent throughout the entire process.
"Samples of the sand and shingle mix were available to all councillors at last Tuesday's council meeting and the report clearly stakes the composition of the material being proposed for the beach recharge."
The council will discuss the concerns at the council chamber, Weeley, on Tuesday evening.
A £30m sea defence project in Essex is being jeopardised by questions over the materials being used, the leader of Tendring District Council has said.