WorldWide Drilling Resource

36 JUNE 2022 WorldWide Drilling Resource® Environmental Monitoring by Thomas Kwader, Ph.D., P.G. Owner, Qwater Well Developer and WorldWide Drilling Resource® Hydrogeologist It is Important to Grout the Upper Portion of Well Casings! In most states, it is a requirement to grout or seal the upper portion of the well casing of drinking water wells. This requirement helps to prevent surface waters from percolating down the outside of the casing into the producing part of the well. There are many good reasons for sealing this annular space including: 1) Preventing surface water from traveling directly to the producing section of the well (open hole or screened section). This surface water may contain fertilizer, oils or grease, bacteria, or viruses from septic tanks, etc. Most water wells are usually drilled using the mud rotary method where the space between the casing is sealed with a thin or low-viscosity Portland cement or viscous bentonite mud/pellets that hydrate and expand when saturated with water. 2) Preventing surface aquifers from draining to lower levels, which may also deplete or lower local water tables. Water wells drilled by the cable tool method can also be difficult to grout from the surface. However, the casing can be “sealed” with the proper casing drive shoe followed by a bentonite mixture placed in a depression around the casing, which will flow with the casing as it is driven into the producing zone of the well. It is also recommended to grout at least the upper three feet of the casing to seal the area around the top of the well. In the past, the upper annulus of the well was generally overlooked and ignored except for the top foot or two, which would eventually start leaking, making the seal repair much more difficult as erosion progressed along the casing. We, as drilling professionals, need to protect our drinking water supplies, lest they become contaminated and drilling wells for drinking purposes may no longer be an option. Tom Tom Kwader may be contacted via e-mail to michele@ ENV Thank you so much, Bonnie. You are amazingly accurate and I appreciate that. If you could make the changes, please. Thank you, Bill MacDonald President/CEO Heron Instruments, Inc. Dundas, ON, Canada