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Non-Tributary Support: Cash Mine Borehole AdrianBrown
<br />coefficient for drawdown around the mine and for stream depletion computation, as this material is
<br />located at the top of the unconfined flow system at the site.
<br />Tahle 4 - Pomsity of Weathered Granndinrite
<br />Rock Type Porosity % Source
<br />Weathered Granodiorite 4.5 t 2.0% Girtet al, 200314
<br />Weathered Granite/Granodiorite 5%-10% Dir, 200715
<br />-Weathered Granodiorite 12% Arel and Tu rul, 200116
<br />Weathered Igneous Rock 5%-30% Carmichael, 199017
<br />Weathered Granodiorite 20% Nara an et all'.
<br />Weathered Granodiorite. 25% Jacobs19
<br />2.7 Dewatering Flow
<br />The rate of flow of water into the Cash Mine has been evaluated by consideration of the rate of fill-up of
<br />the mine. The mine has been dewatered periodically, when the water reached levels that were being
<br />mined, or were being accessed for exploration. The inflow rate to the mine was recently measured to be
<br />1.56 gpm (2.5 acre feet per year), when the water level in the mine and in the dewatering borehole was
<br />approximately 318 feet below ground surface.
<br />Long-term evaluation of rate of fill up of the mine indicates that this flow rate is typical of normal
<br />inflow to the mine; however it is likely that in wet years the inflow may average up to twice this
<br />amount. With the mine fully dewatered (to 552 feet below ground surface) the in flow is expected to be
<br />approximately twice this rate. Based on these estimates, the maximum mine inflow is therefore
<br />estimated to be 6 gpm (10 acre, feet per year).
<br />The dewatering flow rate from the mine depends on the capacity of the pump in the dewatering
<br />borehole. At present, the installed pump is capable of a maximum of 50 gpm against minimal static head
<br />(when the mine is flooded to Level 1) and 20 gpm when the mine is fully drawn down to 552 feet below
<br />ground surface.
<br />When flooded to Level, 1, the mine is computed to contain 13.9 acre feet of water above the dewatering
<br />pump level. If the mine were to be completely dewatered from a flooded state it would require pumping
<br />14 Girty, G.H., Marsh, J., Meltzner, A., McConnell, J.R., Nygren, D., Nygren, J., Prince, J.M., Randall, K., Johnson, D., Heitman, B., and
<br />Nielsen, J., 2003. Assessing Changes in Elemental Mass as a Result of Chemical Weathering of Granodiorite in a Mediterranean (Hot
<br />Summer) Climate. Journal of Sedimentary Research; May 2003; v. 73; no. 3; p. 434-443
<br />1s Dir, 2007. Geotechnical Report On The Occurrences Of Various Types Of Dimension Stones In Different Parts Of Dir, Swat, Bunair,
<br />Shangla, And Mansehra Districts N. W.F.P. Dir Granite Company, 2005.
<br />16 Arel, E., and Tugrul, A., 2001. Weathering and its relation to geomechanical properties of Cavusbasi granitic rocks in northwestern
<br />Turkey, Journal Bulletin of Engineering Geology and the Environment, Vol 60, No 2, July 2001, pp. 123-133.
<br />17 Carmichael, R.S., 1990. Practical Handbook of Physical Properties of Rocks and Minerals. CRC Press, 1990.
<br />18 Narayan, K.A., Hartmann, D., Charlesworth, P., Kemei, J.K., and Bristow, K.L., 2004. Modelling Effects of Val-Bird Weir Height on
<br />Water Tables Along the Haughton River (Burdekin Houghton Water Supply System). CSIRO Land and Water Client Report for
<br />Burdekin Dry Tropics Board, August 2004.
<br />19 Jacobs, 1994. Long-Term Surveillance Plan for the Lowman, Idaho, Disposal Site. Report prepared for the U.S. Department of Energy,
<br />UMTRA Project Office, Albuquerque, New Mexico by Jacobs Engineering Group Inc., Albuquerque, New Mexico, April 1994.
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