[en] The Grout Treatment Facility (GTF) at Hanford, Washington will process the low-level fraction of selected double-shell tank (DST) wastes on the Hanford Site, to produce a cementitious waste form. This facility, which is operated by Westinghouse Hanford Company (Westinghouse Hanford), mixes liquid wastes with cementitious materials and pumps the resulting grout slurry into large [5,300 cubic meters (m³)] concrete vaults. Once in the vault, the grout cures to produce a waste form that immobilizes radioactive and hazardous constituents through chemical reactions and/or microencapsulation. Although this disposal scheme has several advantages, pouring grout into large vaults raises concerns about how to handle the heat generated from the exothermic hydration reactions that occur as the grout cures. WHC's current strategy for addressing the problem of hydration heat is to fill the vault in stages and use forced ventilation in the airspace above the grout to speed heat removal. The varying composition of Hanford tank waste requires that each tank be processed in a separate campaign using a grout formulation specifically designed for that waste. The next tank scheduled for treatment is DST 241-AN-106. A four-phase process for developing the grout formulation development process is used to assure that the formulation will meet various processing and waste form requirements. These phases are: (1) laboratory formulation development studies and modeling with simulated wastes, (2) laboratory variability studies with simulated waste, (3) pilot-scale verification tests with simulated wastes, and (4) laboratory verification tests with actual waste. This paper presents an overview of the pilot-scale verification tests conducted as part of the grout formulation development for the 241-AN-106 tank waste. The paper specifically discusses results dealing with (1) the grout slurry critical flow rate and (2) the ability to handle grout hydration heat with forced ventilation