A scheduled inspection showed that two 8-year-old concrete sludge-holding tanks at the Hopewell, Virginia, wastewater facility were being attacked by hydrogen sulfide fumes. The aggressive vapors had exposed aggregate to a 1-inch depth and had started corroding stainless steel rebars. A polymer-modified portland cement mortar, applied quickly using dry-process shotcreting equipment, was chosen for the repair. The mortar was then protected by a double coat of a chemical-resistant epoxy. The base coat is red, and the top coat is gray. When the gray top coat wears away and red is visible, it's time to recoat.