Grouting & Placement For Geothermal Applications Presented by Stewart Krause Wyo-Ben, Inc. Billings, MT

Why Grout? Prevent surface water from entering aquifers Prevent co-mingling of aquifers Enhanced Loop Performance Fill All Void Spaces In The Annular Space Maintain Moisture In The Annular Space

To establish and maintain a seal against all void spaces of equal or lower permeability than that of the least permeable formation intersected. Match thermal properties of the formations to the grouting materials to maximize loop performance & cost. Objective of Grouting:

Typical Grouting & Earth Material Thermal Conductivities Ref. Dr. Charles Remund Bentonite Grout.40 Neat Cement.55 Dry Bentonite Chips.20 Saturated Bentonite Chips.50 TG85.85 Dry Sand.20 Saturated Sand1.40 Heavy Dry Soil.50 Heavy Damp Soil.75 Heavy Saturated Soil1.40 Average Rock1.40 Dense Rock2.00

Soil Thermal Conductivity Ref. VA Dept of Mines & Minerals

Hole Diameter Squared Divided by 24.5 = Hole Volume in Gallons per Foot EXAMPLE (4.5 inch Hole) : 4.5 x 4.5 = / 24.5=.83 gpf Calculating Hole Volumes

Product Sheets Listed information should include Mixing ratio Density Thermal Conductivity Product Yield

Commonly Used Grouting Materials Cement Grouts High Solids Bentonite Grouts Thermally Enhanced Bentonite Grouts

Cement Grouts Available—Easily pumped—Structural—Easily Probed vs. Heat of Hydration—Subsidence—Shrinkage Commonly Used Grouting Materials

Cement Grouts Neat Cement Engineered Cement Grouts Mix 111

Cement Grouts Neat Cement 5.2 Gallons Water 94# Type 1 Cement

Cement Grouts Engineered Cement Grouts Bentonite Plasticizers Retardant Accelerators Filtrate Control Sand

Cement Grouts Mix gallons water 94# Type 1 Cement 21 oz Super plasticizer 1.04# Bentonite Ref. M.L. Brookhaven National Laboratory

High Solids Bentonite Grouts Pumpability—Low permeability—Cost—Flexible vs. Difficult to probe—Subsidence Commonly Used Grouting Materials

High Swelling Bentonite Products Effectively Create Seals Restricts surface water penetration to lower aquifers Restricts inter-aquifer mingling and artesian flow Keeps moisture around sands in the annular area Fills all void spaces in the annular area

Dispersed –Granular –Powder Encapsulated –Granular High Solids Bentonite Grouts

Thermal Conductivity.43 to.45 Solids Content 15% 20% 30% High Solids Bentonite Grouts

Calculating Solids Content Grout Weight ÷ (Water Weight + Grout Weight) = % Solids (By Weight) Example: 50 ÷ 250 =.20 or 20% Solids 50 lbs. (Bentonite Grout) 200 lbs. (24 Gallons Water) + 50 lbs. (Bentonite Grout)

Flowable High Solids Bentonite Grouts

Develops Gels When At Rest High Solids Bentonite Grouts

With Densities Greater Than Water, High Solids Bentonite Grouts Will Easily Displace Water & Fill Voids

High Solids Bentonite Grout’s Flowable Nature Allow It To Seal Into Voids And Establish An Excellent Bond With All Surfaces.

Thermally Enhanced Bentonite Grouts Pumpable—Flexible—Low permeability vs. Some subsidence—Cost — Labor Commonly Used Materials for Grouting

Thermal 200 lbs. Sand 400 lbs. Sand Solids Content 64% 71% Thermally Enhanced Grouts

Thermal Conductivity Testing

Objective Behind Grouting TO ESTABLISH AND MAINTAIN A SEAL AGAINST ALL VOID FACES, WITH AN EQUAL OR LOWER PERMEABILITY THAN THE LEAST PERMEABLE FORMATION INTERSECTED.

Type Of Grouting Material To Be Placed Depth To Be Placed Local Regulations (allow for pulling the temmie pipe or bottoms up) Specification Requirements (tremmie pipe size limitation) Choosing Grouting Material & Equipment

Equipment

Gear Pump

Progressive Cavity Pump

Piston Pumps

Mud Balance Water Volume Record Keeping Thermal Conductivity Site Testing

Sealing Boreholes While Utilizing Thermal Energy “Is” Protecting Our Children's Future Wyo-Ben, Inc. Billings, MT

Questions ?