[en] This report describes the drilling and testing of Mansfield No. 1 well, located in Oldham County, about 10 miles north of Vega, Texas. Drilling and testing were performed by Stone and Webster Engineering Corporation as a part of a nationwide program to identify potential locations for a nuclear waste repository. This report describes the drilling and testing activities actually performed (compared to the Field Test Plan), describes the problems encountered, and provides recommendations for future work. Data gathered during drilling and testing of the well are included as appendices to this report. Drilling of the well began October 19, 1981. Casing was installed and cemented to a total depth of 5180 feet on March 8, 1982. These data are preliminary. They have been neither analyzed nor evaluated