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APPENDIX A

Issues for Saturated Zone Flow and Transport

Table A-1. Issues for Saturated Zone Flow and Transport

Issue Source PMR Approach
The saturated-zone (SZ) needs additional characterization:

  • Between the repository and the accessible environment 20 to 30 km (12.5 to 18.6 mi.) away.
  • Information about long-range colloid transport,
  • The Nye County Early Warning Drilling Program (NCEWDP) should provide valuable information on the part of the SZ downgradient of Yucca Mountain. However, the wells may not provide sufficient data, and additional testing may be needed at other sites closer to Yucca Mountain.
 Paperiello 1999 ;

NWTRB 1999a;

NWTRB 1999b;

Budnitz et al. 1999
  • NCEWDP was started, in part, to characterize areas between the potential repository and areas 30 km 18.6 mi.) down gradient. The program is continuing. Hydrologic data discussed in Section 3.1.2.
  • Next phases of NCEWDP testing are ongoing and are closer to Yucca Mountain.
Evaluate, integrate, and incorporate alternate models (such as those developed by State of Nevada hydrologists) into coherent SZ model. Cohon 1998b;

Cohon 1999b		 Alternative conceptual models, including the models presented by State of Nevada hydrologists, are evaluated. Discussion in Section 3.8.
Borehole WT-24 drilling was stopped too soon to evaluate the large hydraulic gradient.

Much work was planned to characterize the large hydraulic gradient, but was not done. People will ask why.		 Cohon 1999a;

NWTRB 1998a 		Borehole WT-24 provides sufficient information to determine that the large hydraulic gradient is due in part to perching. The large hydraulic gradient is discussed in Sections 3.2.2.3 and 3.2.5.1.
Warm water in some NCEWDP wells needs investigation. Cohon 1999a;

NRC 1999c		 Warm water is not anomalous compared to other wells in region (e.g., Sass et al. 1988). NCEWDP and U.S. Department of Energy (DOE) investigations are ongoing.
Characterizing effects of molecular diffusion, hydrodynamic dispersion, and sorption on dilution in the SZ will be difficult and may be impractical because it could take many years for the tracers to travel from Yucca Mountain to the monitoring wells. Some data may be obtained from long term tracer test at proposed second SZ well complex. Cohon 1998b Tracer tests have been done using multiple tracers to identify effects. Characterization discussed in Section 3.1; hydraulic well tests in Section 3.1.2.2; tracer tests in Section 3.1.3.2; laboratory data in Section 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.

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