WorldWide Drilling Resource

43 WorldWide Drilling Resource ® DECEMBER 2014 Geothermal Borehole Grouting Without Silica Sand by Peter Tavino Litchfield Geothermal The Baltimore IGSHPA (International Ground Source Heat Pump Association) Technical Conference & Expo was a success, despite our hotel rooms facing Camden Yards while the Orioles base- ball team was being swept in Kansas City. Among the many positive experi- ences with IGSHPA was the GeoPro, Inc. grout booth in the exhibit hall, manned by Allan Skouby and Chuck Remund. Their new product, PowerTECx, looks poised to revolutionize our industry. It is an engineered graphite-based mate- rial supplied in 15-pound bags that substi- tutes for silica sand in the bentonite grout mix. They showed samples in these containers: PowerTECx improves grout thermal conductivity with a range from 1.2 to 1.6 BTU/hr.(ft.)ºF. This translates to less borehole length required by a few per- cent. Lower viscosity during pumping through the tremie line makes life eas- ier for the grout mechanic, and means less wear and tear on the progressive cavity pump. It has been tested safe for nearby potable water supplies, and does not escape into rock crevices easily. A recent issue involving water pH, water content, and mixing time leading to grout settle- ment in the borehole should be avoid- ed. PowerTECx does require precise water volume solution, and hopper tanks should be metered or marked for the exact amount of gallons held to a level line, to achieve proper results. Most of all, we move away from sand pallet delivery to the jobsite. The expansion powers of bentonite in the ground mean material costs will actually be less this way. Trucks, which are at their Department of Transportation weight limits already, need not be concerned about being pulled over by law enforce- ment for weighing. Contractors can haul more bentonite Thermal Grout Lite or Thermal Grout Select 50-pound bags and more water, instead of silica sand. And labor is eased, as workers need not lift hundreds of pounds of sand to the hopper with each batch. Those body builders can get enough exercise with the 50-pound bentonite bags, instead of the numerous 50- and 100-pound sand bags which are not healthy for their lower back spinal muscles. Inspectors like me will enjoy not having to count five bags of sand in each bag of ben- tonite anymore. Geothermal technology marches on! The statements and comments in this article are based on information and references believed to be true and factual. If you have any questions or comments, please forward them to me in care of WWDR . Pete Peter Tavino may be contacted via e-mail at michele@ worldwidedrillingresource.com & ! $ # & # " ! $ # & # & " & ! " & " $ # & & ! & " & & "! " ! & " " ! ! ! !% $ # "! ! 3#-0 $ 0!5&-0$14)**% *-5#%,2%0 *--. .3+. +-$3*%1 !0% !4!)* !"*% &-0 "-2( 0%1)$%,2)!* !,$ #-++%0#)!* '0-3,$ *--. (%!2),' !,$ #--*),' 1712%+1 -+.!2)"*% 5)2( 2(%1% .3+.1 03,$&-1 ) *- *-5#%,2%01 #!, "% #-, &)'30%$ 5)2( -0 .3+. 3,)21 2- +!2#( $)&&%0%,2 *-!$ 0%/3)0%+%,21 0-$3#21 ),#*3$% *-5#%,2%01 %-2(%0+!* *-1%$ --. )22),'1 %.*!#%+%,2 3+.1 -1% )21 !,$ ##%11-0)%1 !0)!"*% .%%$ 3+.1 (-,% !6