PERMEABILITY TESTING OF SIMULATED SALTSTONE CORE AND VAULT 4 CELL E SALTSTONE

The Engineering Process Development Group (EPD) of the Savannah River National Laboratory (SRNL) prepared simulated saltstone core samples to evaluate the effect of sample collection by coring on the permeability of saltstone. The Environmental Restoration Technology Section (ERTS) of the SRNL was given the task of measuring the permeability of cores of simulated saltstone. Saltstone samples collected from Vault 4 Cell E using both dry and wet coring methods were also submitted for permeability analysis. The cores from Vault 4 Cell E were in multiple pieces when they were recovered (Smith, 2008 Cheng et.al, 2009). Permeability testing was only performed on the portions of the core sample that were intact, had no visible fractures or cracks, and met the specifications for 'undisturbed specimens' identified in Method ASTM D5084-03 Standard Test Methods for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter that was used for the testing. Permeability values for cores of simulated saltstone compared with values from permeability tests conducted on molded saltstone samples by an independent laboratory using the same method. All hydraulic conductivity results for Vault 4 samples exceeded results for both molded and cored saltstone simulant samples. The average hydraulic conductivity result for Vault 4 Cell E samples of 3.9 x 10{sup -7} cm/sec is approximately two orders of magnitude greater than that of the simulated saltstone with an average of 4.1 x 10{sup -9} cm/sec. Numerical flow and transport simulations of moisture movement through saltstone performed for the performance assessment of the Saltstone Disposal Facility (SDF) used 2.0 x 10{sup -9} cm/sec for the hydraulic conductivity of saltstone (Flach et al, 2009). The results for simulated versus actual saltstone were further compared using non-parametric statistics. The results from non-parametric statistical analysis of results indicate that there is at least a 98% probability that the hydraulic conductivity of saltstone samples collected from Vault 4 Cell E saltstone is greater than that of the baseline simulant mix