Laser ablation-inductively coupled plasma-atomic emission spectrometry was used for in situ determination of uranium and thorium concentrations in soil at 80 sampling sites in the Sewage Treatment Plant area. This work was performed by the Environmental Technology Development Program of the Ames Laboratory using a completely self-contained mobile laboratory. This laboratory, the mobile demonstration laboratory for environmental screening technologies and the robotic sampling accessory, were designed and constructed by the Ames Laboratory during FY 1992. The instrumentation is capable of analyzing each sample for twenty operator-defined elements simultaneously. Using the MDLEST/RSA, the uranium concentrations in the soil at the 80 sampling sites were found to range from <20 parts-per-million (ppM)(<13.5 pCi/g) to 303 ppM (205 pCi/g). The 95% confidence interval for these field determined values range from 80 to 110 ppM. Bore hole samples from two sites were analyzed. No measurable uranium concentration was detected below the one foot depth. Seven samples taken from sites within an area currently under remediation were analyzed and found to contain uranium concentrations ranging from 101 ppM (68.3 pCi/g) to 788 ppM (532 pCi/g). Soil samples were taken from twelve of the 80 sampling sites in the field, using conventional sampling techniques. These samples …