Solid Waste Management (SWM) operates the E-Area Low-Level Waste Facility (ELLWF) where low level on-site and off-site solid waste streams are buried. The facility has been in operation since late 1994 and is currently projected to remain in operation until 2065. This facility can accommodate a broad range of waste forms resulting from the six different types of disposal unit options (i.e., varying degrees of engineered barriers trenches to concrete vaults). This facility is currently operating under a Performance Assessment (PA) issued back in 2008, along with several subsequent supporting Special Analyses (SA). The Savannah River National Laboratory (SRNL) developed the prior PAs and SAs and has been tasked to update the facility's PA. For operating the E-Area facility, a Waste Inventory Tracking System (e.g., WITS) is actively employed by waste generators where every radionuclide entering the facility (to be buried in one of its many disposal units 1) must be either directly or indirectly accounted for. Since there is a large number of radionuclides in existence (>3,000), the International Commission on Radiological Protection (ICRP-107) has provided guidance on the subset of radionuclides requiring further assessment in landfills such as the E-Area LLWF. The ICRP-107 publication provides critical radiological information on 1,252 radionuclides of 97 elements. This database is the critical starting point for developing a consistent inventory limit system. SRNL-STI-2020-00174 Revision 1 vi In this new screening effort, the performance measure has been tightened up by: Consistently looking at every exposure pathway regardless of the tier level; and Requiring that a pathway's maximum exposure not exceed 0.1% of the applicable performance measure (e.g., 0.1% of the 4 mrem/y performance measure x 0.001 = 0.004 mrem/yr) over the entire period of performance. Bullet one ensures that no inconsistencies creep in between varying tiers such that a radionuclide passed on to the PA-level analysis would not have been first screened out at a higher level. Bullet two provides additional risk reduction in the very unlikely scenario that a set of radionuclides screened out from further consideration in a pathway would produce a cumulative dose impact approaching the applicable performance measure. In developing an overall inventory limits system a tiered approach is most efficient with respect to its acceptance and maintenance. For example, if the tracking of a significant number of radionuclides can be omitted through relatively simple, but accepted, arguments/models the overall costs are greatly reduced. The overall structure of the E-Area tiered inventory limit system is: Tier-0-Establishment of an upper closure inventory projection Tier-1-"NCRP-like" groundwater and intruder screening (very conservative) Tier-2-Simple, but bounding, 1D transport modeling (conservative) Tier-3-Generic waste (multi-D, no credit taken for any possible engineering barriers) Tier-4-Special waste form (multi-D, credit taken for ce...