The cavity definition study of the first test of the DOE UCG-SDB program, provided results to plan, install, instrument and monitor the second test at Rawlins, Wyoming. The successfully completed test met all its objectives and set the stage for future multi-module tests. The cavity definition program for the second test has been conducted by the LETC with input from GR&DC. The complete results of this program are not yet available. The present report has tried to project the shale and volume of the UCG created cavity, and the bulking factor of the rubble in the UCG affected area, utilizing the LETC information available to date.