In this ‘Geothermal Demystified’ series, we are hoping to shed some light on how geothermal systems are installed and how they perform in New England. It’s surprising how often the same questions and comments arise. In this post, we will address two more geothermal myths having to do with local geology.
Myth #3 My property is on ledge and you can’t drill through bedrock.
False! Drilling through bedrock is no problem. Our drilling contractors drill through bedrock all the time. That’s how most water and irrigation wells are installed. An experienced driller can drill between 200 and 300 feet in one day! In a lot of places in New England, bedrock will be encountered within the first 50 feet.
Ledge can sometimes be a problem when it’s encountered between the drilling location and the foundation wall. We usually like to have all piping greater than 3 feet below surface grade. We want to protect the pipe from digging or excavation activities that might be associated with landscaping. It also helps protect the pipe from vehicular traffic when pipes are present beneath drive-ways or parking areas. The depth is more about protecting the pipe from puncture or crushing risks rather than freeze protection.
Myth #4 My whole neighborhood sits on bedrock. Drilling will ruin all the foundations my neighborhood.
Bedrock has been encountered on every single geothermal installation that we have ever completed. To my knowledge, no foundation damage has ever been observed – even when the borings were advanced within 10 to 15 feet of a foundation wall. It is extraordinarily unlikely that foundation damage will occur on neighboring properties.
Geothermal boreholes are created by cutting and grinding a 6-inch core through the bedrock. There is no blasting, hammering, or pile driving. It will not cause an earthquake. It will not rattle the entire neighborhood.
Have you heard something about geothermal that you’re not sure about? Send us your questions!