Solid soil matrix (Bentonite) | Saturated/intrinsic permeability, *k*_{ij} (m^{2}) | 3.40E−21 |

Dry density, *ρ*_{d} (kg m^{−3}) | 1560 |

Maximum degree of saturation, *S*_{ws} | 1 |

Residual degree of Saturation, *S*_{wr} | 0.05 |

Porosity, *n* | 4.40E−01 |

Young's Modulus, *E* (MPa) | 307 |

Poisson ratio, *ν* | 0.4 |

Bulk Modulus of bentonite, *K*_{s} (Pa) | 2.0E + 08 |

Compression Index, 1/*K*_{s}(Pa^{−1}) | 5.00E−09 |

Volume-surface mean diameter, *D*_{vs} (m) calculated based on equation (23) | 1.50E−09 |

Initial tortuosity, *τ* | 0.69 |

Gas (Helium) | Density, *ρ*_{g} (kg m^{−3}) | pgMRT |

Dynamic Viscosity @ 293.15 K (Pa s) | 2.0E−05 |

Bulk Modulus of helium, *K*_{g} (Pa) | *p*_{g} |

Henry's Coefficient, *H* | 0.0091 |

Diffusivity of helium in water (m^{2} s^{−1}) | 6.29E−09 |

Diameter of helium gas particle, *d*_{he} (m) | 1.0E−10 |

Liquid (Water) | Density, *ρ*_{w} (kg m^{−3}) | 1000 |

Dynamic Viscosity @ 293.15 K (Pa s) | 0.001 |

Bulk Modulus of water, *K*_{w} (Pa) | 2.2E + 09 |

Compression Index, 1/*K*_{w} (Pa^{−1}) | 4.55E−10 |