The computer automated surveillance system (CASS) connects instruments located in most of the underground tanks and vaults containing nuclear wastes to a centralized computer room where periodic readouts are monitored for any change in status. Data is collected and monitored automatically. Microprocessors located in the tang farms collect and transmit data to the central computer. The operator on duty monitors frequent regular reports. A second computer also routinely processes data from the wells around the tanks. Historical USDE.