This calculation was performed to provide a screening-level assessment of long-term human health risk associated with potential leakage that could occur during tank S-109 partial waste retrieval operations in support of a planned treatment demonstration. This calculation supports the development of tank S-109 partial waste retrieval functions and requirements as documented in RPP-18812. Evaluation of the risk associated with the current waste and potential residual waste in tank S-109, as well as the risk associated with the other S farm tanks, were not included in the evaluation. Evaluation of those risks is deferred to the analysis supporting final tank S-109 waste retrieval.