1.1 SCOPE

1. A vertical bore shall be installed according to these specifications. The completed bore shall be located so that it is incorporated into the final ground-loop heat exchanger design. A completed vertical test bore shall consist of the vertical bore with an approved polyethylene u-bend assemble installed to the completed bore depth with an approved grouting material installed in the bore annulus.
2. Vertical bore can be drilled either by a mud-rotary drilling rig or by a compressed-air drilling rig which ever is most feasible based on geological conditions.
3. Drilling contractor shall provide a detailed test bore report. The report shall include the following information:

1. Each formation type encountered (drill log)

2. Each formation depth (in feet)

3. Depth of any significant cracks, fissures or caverns encountered

4. All water bearing zones and if encountered:

1. Zone depths

2. Estimated flow rate

5. Type of drilling equipment used (i.e. mud-rotary, air-rotary, air-hammer, etc.), and rig model number

6. Bag quantity of drill mud used where applicable

7. Total time to drill the test bore excluding shut-downs to obtain water or mechanical break-downs.

A completed, signed report shall be supplied immediately at the conclusion of the drilling process.

1. Drilling contractor shall be responsible for all permits and following all applicable codes and regulations. Where any discrepancy exists between local codes and regulations and this specification, the more stringent of the two documents prevail.
2. Drilling contractor shall take all necessary precautions to protect the site from any damage resulting from the drilling operation.

1.2 BORE DIAMETER

1. The diameter of the vertical bore shall not be greater than 6 inches (152.4 mm) and shall not be less than 4.5 inches (114.3 mm). The final diameter shall be determined by the drilling contractor's available equipment.

1. The completed bore depth shall be within 5% of the final estimated design bore depth for the specific project. The completed depth shall be determined by the placement of the u-bend. The distance from the bottom of the u-bend to the surface shall constitute the completed bore depth. At minimum, an additional 5 feet (1.52 m) of pipe length (on both the supply and return legs) shall be left above the installed u-bend assembly, above ground level/finished grade.

1. The polyethylene u-bend assembly shall be manufactured from a polyethylene extrusion grade material having a minimum cell classification of PE345434C per ASTM D-3350 and shall fully comply with the ISGHPA standard 1C "Ground Heat Exchanger Materials". The u-bend shall be factory assembled and pressure tested to 100 psi prior to insertion into the vertical bore. The u-bend pipe diameter shall be 3/4 inch (19 mm), 1 inch (25.4 mm) or 1-1/4 inch (31.8 mm) IPS-OD as determined from the table below:

1.5 GROUTING MATERIAL

1. The annular space between the vertical bore wall and the u-bend assembly shall be filled with a bentonite-based grouting material with a minimum solids content of 20%. The grouting material shall be mixed in strict accordance to the manufacturers mixing instructions. Grouting material shall be placed using a pressure pump with a tremie pipe system. The material shall be installed from the bottom to the top of the vertical bore. If any settling occurs during the initial 24-hour period after installation, additional material shall be added to insure that grouting material remains at surface level.
2. In the event that a geological formation is encountered that prevents the grouting material from forming a solid seal, either a 3/8 inch (9.5 mm) or 3/4 inch (19 mm) granular bentonite material may be use through that specific formation zone. Upon completion of that specific zone, the grout slurry shall continue to be use until reaching the surface of the vertical bore.
3. Grout manufacturer and percent solids shall be reported immediately following bore completion.

2.1 SCOPE

1. The formation thermal conductivity test is designed to determine the average thermal conductivity of the formation for the completed bore depth. A contractor and/or affiliated organization, with at least 10 successfully completed tests prior to performing this test, shall perform the test. A list of previous tests shall be supplied upon request.
2. The testing device shall be designed so that a constant rate of heated water is supplied in an uninterrupted fashion to the u-bend assembly.
3. The testing device shall have the capability of automatically collection data at predetermined intervals. Collected data shall be available to the design engineer in an electronic format compatible with Microsoft Excel®.

1. The testing device shall be designed to prevent as much heat loss to the environment as possible. Each end of the u-bend assemble shall be insulated with a closed-cell insulation to prevent heat loss or heat gain.

2.3 ELAPSED TIME BEFORE TESTING

1. AIR ROTARY DRILLING: A minimum delay of five days between loop grouting and testing is required.

2. MUD ROTARY DRILLING: A minimum delay of three days between loop grouting and testing is required.

2.4 INPUT HEAT RATE

1. The testing device shall be designed so that a constant rate of heat input into the vertical u-bend assemble shall be no less that 51 Btu/hr (14.9 W) per bore foot. If a lower rate is anticipated, prior approval must be obtained before hand. In any event, the heat rate shall not fall below 45 Btu/hr (13.2 W) per bore foot. Heat rate shall not be altered during the duration of the thermal conductivity test. The selected heat rate shall not be greater than 85 Btu/hr (24.9 W) per bore foot.

2. The average input heat rate shall be reported in the final analysis.

1. Data shall be taken at a frequency of no more than every 5 minutes throughout the duration of the test. Data collected shall consist of the following as a minimum; temperature into the loop, temperature out of the loop, ambient air temperature within the test unit compartment, ambient outdoor air temperature and watts.

2.6 TEST DURATION

1. The duration of the formation thermal conductivity test shall be a minimum of 40 hours from the initial starting time. Power interruptions shall be avoided whenever possible.

2. In the event an interruption occurs which lasts longer than 15 minutes, power should be restored as soon as possible and the test continued to predetermined conclusion. Provisions shall be made to run the test again based on the analysis of the collect data. In such event, the vertical bore shall be allowed to thermally rest for a period as determined from the table below:

Select the "Run Time" which is just greater than actual hours 

then use the associated "Rest Period" below.