A moisture barrier using water, sodium silicate, formamide, calcium chloride and penechem with a gel time of one-half hour was constructed around a simulated tank 10 feet deep by 10 feet diameter in the subsurface of the 200 West Area. As a test of the moisture barrier integrity, the volume which would normally be occupied by a tank was excavated and filled with water. The barrier was unable to contain the water. The failure to achieve a water-tight barrier was attributed to a leak in the floor grout.