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The one-dimensional compression method for extraction of pore water from unsaturated tuff and effects on pore-water chemistry

Technical Report ·
DOI:https://doi.org/10.2172/653994· OSTI ID:653994
;  [1];  [2]
  1. Colorado School of Mines, Golden, CO (United States)
  2. Geological Survey, Denver, CO (United States)
Study of the hydrologic system at Yucca Mountain, Nevada, requires extraction of pore-water samples from unsaturated tuff bedrock. Two generations of compression cells have been designed and tested for extracting representative, unaltered pore-water samples from unsaturated tuff cores. The one-dimensional compression cell has a maximum compressive stress rating of 552 MPa. Results from 86 tests show that the minimum degree of saturation for successful extraction of pore water was about 14% for non welded tuff and about 61% for densely welded tuff. The high-pressure, one-dimensional compression cell has a maximum compressive stress rating of 827 MPa. Results from 109 tests show that the minimum degree of saturation for successful extraction of pore water was about 7.5% for non welded tuff and about 34% for densely welded tuff. Geochemical analyses show that, in general, there is a decrease in ion concentration of pore waters as extraction pressures increase. Only small changes in pore-water composition occur during the one-dimensional extraction test.
Research Organization:
Geological Survey, Denver, CO (United States)
Sponsoring Organization:
USDOE Office of Civilian Radioactive Waste Management, Washington, DC (United States); Geological Survey, Reston, VA (United States)
DOE Contract Number:
AI08-92NV10874
OSTI ID:
653994
Report Number(s):
USGS/WRIR--96-4281; ON: DE98005240
Country of Publication:
United States
Language:
English