By Allen Hibner: April 22nd, 2021- This image shows THE FINAL DAY of drilling six (6) 100’ deep wells for our new WaterFurnace geothermal system installation.
While I strongly encourage you to watch the video that I have made documenting the drilling of the six wells on our property, if you don’t end up getting a chance to view it, I wanted to summarize the main things that I learned about this amazing process for you in this blog article.
What I discovered about the geothermal well drilling process:
My home sits on a hill (Highledge Drive in Penfield) that was formed by glacial action as the glaciers retreated north thousands of years ago. It may be considered a “drumlin” and consists of a lot of the debris left behind as the glacier retreated. Because of this, the drilling crew found different geological conditions in EACH WELL, even though they were only 10’ apart. They encountered top soil, gravel, sand, loose rocks and boulders along with pockets of water before hitting bedrock. They told me that no two wells that they drilled on our property were the same. Because of this dramatic variability in conditions, it made the drilling of my six wells quite challenging for them. Indeed, at two and a half weeks onsite, my backyard became the longest and most difficult residential geothermal well site they had completed to-date per their comments to me as they were leaving.
In my backyard near the top of Highledge Drive in Penfield, bedrock sits at around 102’ below the surface of the earth. The drilling crew told me that on well #1, the plan had been to drill down to 150’. They hit bedrock at 102’ and kept drilling into it. However, it took them an hour to drill just 5’ further into the bedrock. That is what caused them to revise the drilling plan to (now) drill 6 – 100’ wells instead of 4 – 150’ wells – it simply would have taken too long to finish the wells as originally planned. I learned that drilling plans for geothermal system installations are frequently subject to change based on the reality of the geology that they encounter at a given site. Fascinating!
I learned that when drilling a well, the crew first sinks outer “auger” sections (you can see them lying on the ground in the picture above) into the ground. The purpose of doing so was to place the hollow augur “shaft” below the gravelly part of the ground. Gravel causes the drill shaft to collapse and make it so that the thinner hollow core drill shaft and drill bit would be unable to proceed to the proper depth. What the drilling crew told me is that the auger sections were usually, in my backyard, sunk to a 40-60’ depth in a given well to go below the gravel. Once set, they could then proceed drilling with the inner hollow core drill shaft and bit to the desired 100’ depth. The crew also learned early on that they would need to utilize a mixture of water and Bentonite drilling “mud” to keep the drill bits from clogging up completely. Despite the addition of the drilling mud, I actually did see them one time need to lift the entire inner drill shaft and bit up to the surface and blow out the hollow core drill bit before proceeding to the final depth for that well. That took quite a bit of extra time to do as you can imagine.
This image shows the augur sections on the right and the hollow core
inner drill shaft sections on the left. The drill bit (see next image) was
threaded onto the shaft at the bottom of the well.
This image shows the hollow-core drill bits used in drilling.
The drilling “mud” mixture is sent down the hollow drill shaft and
exits out of the holes in the drill bit to prevent the bit from clogging up.
Once a well was completed, the crew would take a 100’ roll of HDPE (High Density Poly-Ethylene) pipe and push it down the well shaft. They would fill the ¾” diameter pipe with water to keep it from floating back up and out of the shaft. Actually, they usually also tied the pipe to the top most augur section to secure it overnight from escaping back out of the well along with taping shut the ends of the pipe sticking out of the ground to prevent any loose dirt or drilling mud from getting inside the pipe which might contaminate the ground loop’s fluid later.
100’ roll of HDPE pipe shown – forms a “U” at the bottom of the well
So that the fluid descends and then ascends back up the well “loop.”
Therefore, a 100’ well = 200’ of HDPE pipe
In this image, the crew has finished drilling for the day.
They have lowered the HDPE pipe down the well and tied
it to the top-most augur section with orange tape so it
will not float back up and escape out of the well.
I observed that the drilling crew would leave the HDPE pipe secured to the top-most augur section overnight so that the drilling mud (water and Bentonite) in the well shaft would saturate with water, setup or solidify and encapsulate the plastic pipe. This is important because of the need to ensure proper thermal transfer from the ground to the pipe. There cannot be any air pockets surrounding the plastic piping, since that would reduce the efficiency of the closed ground loop. The next day, after the HDPE plastic pipe had setup properly in the well, the crew used their drilling rig to gently pull up all of the augur sections and remove them one-by-one without disturbing the ground loop pipe they had put in place the prior day.
Finally, I learned that drilling geothermal wells takes an amazing amount of experience and skill. The drilling crew on our job even told me that they had consulted a 30+ year drilling veteran in their company for thoughts on how best to drill our wells. 85 Highledge Drive, Penfield, challenged them quite a bit, but in the end, they tamed my “glacial geologic monster” and drilled it into submission (no pun intended). I was extremely impressed with how hard the crew worked in all types of conditions and just how skilled and creative they were at finishing this job. Truly, this is an amazing (and growing) “green job” for the future. As people all over this nation adopt geothermal heating and cooling systems for themselves, for their …ALL-ELECTRIC-Lives… Many, many more people will be needed to do this work. There is simply no reason that people drilling oil and gas wells now cannot move laterally and quickly into drilling geothermal wells for homes and businesses. Our family is adopting this technology quite early in the game, but it is no stretch to see how quickly this business will grow. I have seen the future of sustainable home heating and cooling and it is “geothermal!”
If you are interested in a lot more detail and “live action” on how the wells were drilled, watch the video on YouTube now – CLICK HERE TO WATCH THE VIDEO.
Pretty amazing, wasn’t it? In my next blog article in this Geothermal System Installation Series, I will document the start of the actual installation phase of this project in much greater detail with another YouTube video. You will see how the crews dig the trenches so that they can tie all six wells together and bring the closed geothermal loop into our home where it will be connected to the WaterFurnace to provide sustainable, totally “de-carbonized” all-electric heating and cooling for the Hibner family.
Thanks so much for reading the articles and watching the videos in this series. I hope they are helping you to consider going ALL-ELECTRIC for your own home heating and cooling system needs.
Again, as always, where can you obtain even more local assistance to explore geothermal or ground-source heat pumps? We have a phenomenal resource right here in the Rochester regional area. I strongly encourage you to visit HeatSMART Monroe of the Finger Lakes to learn more.
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