From: stephen@sprunk.org   
      
   On 16-Apr-14 15:11, mroberds@att.net wrote:   
   > Stephen Sprunk  wrote:   
   >> Find (or build) a lake on the surface, drill down a few thousand   
   >> feet and excavate a cavern.   
   >   
   > How do you keep the water from soaking into the rock?  Is the rock   
   > down there tight enough to prevent it, or do you need some kind of   
   > coating on the cavern walls?   
      
   It probably depends on how deep and/or on what type of rock; a   
   containment vessel (probably concrete) would prevent water or   
   contaminants from entering or exiting the cavern through the walls.   
   Depending on the size of the cavern and the stability of the rock, you   
   might need to do most of the work anyway to prevent it from collapsing.   
      
   S   
      
   --   
   Stephen Sprunk         "God does not play dice."  --Albert Einstein   
   CCIE #3723         "God is an inveterate gambler, and He throws the   
   K5SSS        dice at every possible opportunity." --Stephen Hawking   
      
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