More than 5 300 000 ℓ (1400 000 gal) of phosphate/sulfate waste (PSW) grout were produced and placed in vault 101 at the Hanford Site. This waste was generated during decontamination operations and maintenance of the fuel storage basin at the N Reactor. The low-level radioactive liquid wastes were mixed with a blend of portland cement, fly ash, and clays. Through cementing and pozzolanic reactions with water, the grout was solidified to immobilize contaminants and retain low permeability to groundwater. Testing conducted before the campaign is described. The usefulness of each quality verification technique is discussed, focusing mainly on data from the core samples. These data provide the best information on PSW grout since core samples from all regions and depths in the vault were tested. The nondestructive testing data are also useful as they provide property data from broad regions of the vault. The mean compressive strength of the PSW grout cores is 4.17 MPa (605 lbƒ/in.2), much higher than the criterion value of 0.35 MPa (50 lbƒ/in.2). Results also show that the leachability indices for 137Cs, 60Co, sodium, and SO4 for PSW grout cores exceed the leachability criterion [American Nuclear Society (ANS) 16.1 leach indices ≥ 7] by at least one index point. This means that the ability of the grout to resist leaching of waste species is at least ten times greater than the limiting criterion. The facility is nearly ready to begin solidifying higher activity mixed waste; however, the program is being reevaluated to determine whether this increased scope of work is appropriate.