Initially, the Wilsonville facility consisted of a single stage (thermal) process, also known as the SRC-I process. The original plant has been expanded to become an advanced two-stage coal liquefaction facility. A Critical Solvent Deashing (CDS) unit was installed in 1978 and a second stage catalytic hydrogenation (HTR) unit was installed in 1981. The principal product of the first stage is a low sulfur solid fuel. The reaction product is deashed by the CSD unit using a proprietary process developed by the Kerr-McGee Corporation. The hydrotreater, or the second stage, was installed primarily for further enhancement of product properties, process flexibility, and overall hydrogen utilization efficiency. In the decoupled mode of operation, the HTR unit has no direct effect on the SRC unit. This operating mode is called the non-integrated two-stage liquefaction (NTSL) process. From 17 October 1981 to 14 October 1982, the Advanced Coal Liquefaction R and D Facility at Wilsonville, Alabama, was operated partly in support of the 6000 TPD-I demonstration plant design effort undertaken by ICRC. The ICRC support tests and operations performed were: Run 235 with Kentucky 9 (Fies) coal; Run 240 with Illinois 6 (Burning Star) coal; CSD unit second stage variability study; CSD unit continuous ash removal system study; SRC solidification test; wastewater sampling operation; and residual fuel oil blending operation.