The sludge plant, is located on the banks of the River Rouge
Like most abandoned buildings in the crumbling conurbation of Old Detroit, it has only been partially decommissioned and power and services are still active. It's the perfect place for a hideout by the nuke cult.
Duffy told RoboCop that he can find Cain there. He found it heavily defended with minefields, armed members, machine guns and many covers and vantage points. He attempted to arrest Cain but he was shot by Hob and immobilized by Angie. Using the facilities of the plant, cult members managed to tie him down and dismantle his parts.
When RoboCop recovered from Dr. Juliette Faxx's programming, he united the Detroit Police Department and ended their strike. Anne Lewis also remembered what happened to him when her former comrade Lt. Hedgecock was following the corrupted OCP executive Dick Jones' orders to destroy him and she killed him. They raided the plant while Cain was presenting chemist Frank's varieties of nuke. During the fray Hob and Angie escaped in a van.