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Non-Tributary Support: Cash Mine Borehole AdrianBrown
<br />total porosity of 2%. The drainable porosity is estimated to be half the total porosity, or 1%. These
<br />values will be used to characterize the un-weathered rockmass in the vicinity of the Cash Mine.
<br />Table 3 - Porosity of Granodiorite and Igneous Rocks
<br />Rock Type Porosity % Source
<br />Meta- ranodiorite/Granite 0.45% Savukoski, 2004
<br />Igneous Rock 0-5% Freeze and Cherry, 1979'
<br />Granite 0.5%-1.5% Mining Engineer's Toolbox
<br />Granite 1% Schild et al, 2006
<br />Granodiorite 1% Morrow and Lockner
<br />Granodiorite 1% Schneebeli etal.11
<br />Granodiorite Intact 2.3% Sato, 1999
<br />Granodiorite/Granite 1.8%-4.3% Fujimoto et al.
<br />2.6.2 Porosity of Decomposed Granodiorite
<br />The upper approximately 50 to 100 feet of the Boulder Creek granodiorite is weathered. The weathering
<br />process in granodiorite results in oxidation of (particularly) feldspar materials from within the rockmass,
<br />and removal of the resulting oxidized material by dissolution (see for example Girty et al, 2003).
<br />Oxidation is preferential, occurring first on crystalline and phenocryst boundaries. Weathering results in
<br />partial to complete disaggregation of the rockmass particles, and is generally more advanced along joint
<br />and fault planes.
<br />The porosity of the weathered material is greater than the porosity of the intact material, and can be
<br />estimated by reference to experience in this material. The published data on porosity of weathered
<br />granodiorite is summarized on Table 4. The data have been drawn from a wide range of settings, from
<br />slightly weathered rock to completely disaggregated weathered granodiorite. For the Cash Mine area,
<br />the weathered granodiorite is generally still intact, with localized more complete weathering, so a
<br />porosity of 10% appears appropriate for this location. It is estimated that half of this porosity is
<br />drainable, resulting in a drainable porosity of 5%. This porosity is used for the determination of storage
<br />6 Savukoski, M., 2004. Forsmark site investigation, Drill hole KFM01A, Determination of porosity by water saturation and density by
<br />buoyancy technique, Swedish National Testing and Research Institute, January 2004
<br />' Freeze, R.A., and Cherry, J.A., 1979. Groundwater. Prentice Hall, Englewood Cliffs, New Jersey.
<br />8 Mining Engineer's Toolbox, http://www.mininglife.com/Miner/general/rock_porosity.htm
<br />9 Schild, M., Siegesmund, S., Vollbrecht, A., and Mazurek, M., 2001. Characterization of granite matrix porosity and pore-space
<br />geometry by in situ and laboratory methods, Geophysical Journal International, Volume 146 Page 111, July 2001
<br />10 Morrow, C.A., and Lockner, D.A., 2006. Physical Properties of Two Core Samples from Well 34-9RD2 at the Coso Geothermal Field,
<br />California, USGS Open-File Report 2006-1230, 2006.
<br />" Schneebeli, M.; Fluhler, H.; Gimmi, T; Wydler, H; Laser, H-P; Baer, T; 1995. Measurements of water potential and water content in
<br />unsaturated crystalline rock. Water Resources Research, Volume 31, Issue 8, p. 1837-1844, 1995.
<br />12 Sato, H., 1999. Matrix Diffusion of Simple Cations, Anions, and Neutral Species in Fractured Crystalline Rocks, Nuclear Technology,
<br />Volume 127 • Number 2 • August 1999 • Pages 199-211
<br />13 Fujimoto, K.; Takahashi, M.; Doi, N.; and Kato, O., 2000. High Permeability of Quaternary Granites in the Kakkonda Geothermal
<br />Area, Northeast Japan. Proceedings World Geothermal Congress 2000, Kyushu - Tohoku, Japan, May 28 - June 10, 2000
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