Neil Kennedy locked himself by the neck to the front gate of the construction site, and was joined this morning by around 30 local and regional supporters.

His actions came as protesters opposing a coal seam gas wastewater plant in the area declared they aren't giving up their cause any time soon.

"I don't think it's right that Santos can build this waste water treatment plant, with all the risks involved, while a court case is still underway to sort out whether its approval without a proper environmental assessment was lawful or not," Mr Kennedy said.

"I've got 13 grandchildren, and they're good little blokes and I'd like to think they've got a future out here.

"The fact that Santos is pushing on with construction while the approval is the subject of a pending court case suggests the company is overly confident of an ultimate approval. Why can't they wait for due process before they press on in the face of so much opposition and legal uncertainty?

"If an old farmer is chaining himself to someone else's gate, maybe that will show them how much our artesian water means to us, and how seriously we will fight to protect it, if the Government won't."

On Monday police used pepper spray on 47-year-old Kerri Tonkin from South Australia, who had attached herself to an excavator and refused to leave the site.

"The actions of the police officers were excessive and dangerous," Ms Tonkin said in a statement on Tuesday.

Ms Tonkin and fellow protester Cyd Fenwick, 46, who was also fastened to the excavator, were both arrested and charged with trespassing.

Sixteen protesters have been arrested in the past month, according to the Pilliga Action Camp.

Santos said in a statement on Wednesday the protests are illegal and it has strong support from the Narrabri community.