Table A-1. Issues for Saturated Zone Flow and Transport (Continued)
| Issue | Source | PMR Approach |
| SZ modeling needs more model integration and reality checking using data from the site. | Cohon 1998b | Model validation now includes comparisons of: permeability data to calibrated permeability values, fluxes from regional models with fluxes from calibrated model, measured upward gradient with predicted upward gradient, hydrochemical data with calculated particle pathways, and natural analogs. These activities and process model uncertainties are discussed in Section 3.4. |
| Current estimates of SZ dilution eventually may prove to be conservative, but supporting a larger dilution factor will be difficult unless new data are obtained. | NWTRB 1999b | More data have been obtained from multi-well, multi-tracer tests, and work continues to collect more data. Characterization discussed in Section 3.1; hydraulic well tests in 3.1.2.2; tracer tests in 3.1.3.2; laboratory data in 3.1.4. Transport and transport processes discussed in Sections 3.2.4, 3.3.2, 3.3.4, 3.5.2, and 3.6.3. |
| Presentation reported "Gamma spike" in geophysical logs in borehole NCEWDP-3D in conjunction with high uranium content. | NWTRB 1999c;NRC 1999d [Nye County Presentation] | NCEWDP investigations and DOE work are ongoing. |
| Presentation indicated that driller’s log for old Washburn Well (approximately north of Town of Amargosa Valley) predicted about 91 m (300 ft) to water; however, it went to 248 m (815 ft) and did not hit water. NCEWDP to investigate this anomaly. | NWTRB 1998c [Nye County Presentation] | NCEWDP could not reenter original Washburn hole (caved too much and liability concerns). NC-Washburn-1X was sited about 400 m (0.25 mi.) from the original Washburn Well site, drilled to a depth of 200 m (658 ft), and the static water level in the well after completion was 107.8 m (353.8 ft) below land surface. (Hole elevation: 823.5 m [2701.7 ft] above mean sea level determined by Global Positioning System). Water table altitude about 716 m (2,350 ft) at NC-Washburn-1X is consistent with regional trends (Nye County Nuclear Waste Repository Project Office 1999). No water table anomaly noted in new hole. Possible anomaly does not appear to have regional significance. No further Nye County investigations indicated at this location. |
| Concerns expressed regarding transparency of stream tubes model of SZ flow and transport model. | NWTRB 1998b | New three-dimensional (3-D) finite element site model developed; evolution of model discussed in Section 2; improvements to old model discussed in Section 2.5. |