Streaming calculations were performed with both the deterministic Attila solver and MCNP® using Attila4MC (referred to herein as Attila4MC) FW-CADIS variance reduction simulating a cylindrical gamma volume source surrounded by an iron shell behind a concrete wall with an offset penetration shaped similar to those implemented at the Waste Treatment & Immobilization Plant Project (WTP), colloquially known as a ‘joggle.’ Three tissue slab models were placed on the opposite side of the wall. Dose rate results were generated for both Attila and Attila4MC. Results from a CSG (constructed surface geometry) MCNP calculation were also included to validate the unstructured mesh results, generously provided by Jeffrey Dahl of Bechtel Corporation.