I spoke about the benefits of installing deep well seals in confined aquifer wells at this past year’s BCGWA convention. Part of this is to protect against artesian flow and also to prevent co-mingling of waters between aquifers. I’ll speak here about the special case of flowing artesian wells.
Flowing artesian wells are found throughout much of North America, and British Columbia is no exception. From the far north, to the interior to the coastal regions, there are numerous flowing wells. The Okanagan Valley has a number of relatively low pressure flowing wells, some dating back decades. One (in)famous well, located at Coldstream Ranch, that was drilled into a high pressure (> 10 PSI shut in pressure) formation was finally decommissioned last year at a cost that was probably more than $1 million. I recently visited the site of another 1980s sinkhole-former near Enderby in the North Okanagan. Elsewhere, there have been relatively high profile (for groundwater anyway) cases of uncontrolled flowing wells. A few years back, in Chetwynd, and more recently, in Vancouver and one this past spring was drilled in the Westwold area. These are but a few examples.
I view uncontrolled flowing wells as largely avoidable problems. When an uncontrolled flowing well happens, this reflects poorly on our industry, and does not increase public confidence in groundwater resources – not to mention being a waste of water in this era of the Water Sustainability Act. I think the groundwater industry can and should do better to avoid these problems. The best ways to do this are by getting educated and thinking ahead. As always, the path forward is for all of us to work together: drillers, pump installers, consulting hydrogeologists and our partners in other associations and in government.
For those less familiar with artesian flow, here is a brief primer. Wells flow at the surface from confined aquifers because the pressure head in the aquifer is greater than the land surface elevation, and the aquifer occurs below a confining layer (or aquitard) that has sufficiently low vertical permeability to contain the pressure. A properly completed well in a flowing formation must have an annular well casing seal that extends from surface down into the confining unit, and the well casing and the seal must be in place prior to drilling out the lower hole. This requires advance knowledge of the formation, and planning for a higher well completion cost than wells drilled in confined formations that do not flow at the surface. An uncured bentonite surface seal often is not competently adhered to the formation to hold back higher pressure artesian flow.
So, how would a driller know when a deep well seal is required? One answer to that is as more and more wells are registered with the Province, the knowledge of where artesian conditions are found will improve, and our Ministry staff can expand flowing well advisories to more and more areas. The second answer to this is for the well driller to either conduct a pre-drilling assessment, or contact a qualified hydrogeologist to conduct a pre-drilling assessment of the potential for flowing artesian well conditions. Plus a quick call to regional groundwater staff would also be a good idea. Even though the current Water Sustainability Act regulations place some of the responsibility for flowing wells on the well / landowner, in reality, these laypeople are relying on all of us in the groundwater industry to provide them with professional advice and services, and at the end of the day, they expect (and deserve) to be provided with wells that comply with regulations. If this means a higher upfront drilling cost, so be it. Those costs should be passed on to the customer, and is part of doing business in some places in order to access water that would be very inexpensive (or free) to obtain thanks to the natural pressure.
An improperly constructed well completed in a flowing artesian aquifer creates a host of problems that have to be dealt with, all of which cost time and money. In the worst cases, uncontrolled flow outside of the unsealed well casing causes surface and subsurface erosion, ground subsidence (“sinkhole” formation) threatening property and public infrastructure, discharge of turbid water to watercourses, and can jeopardize property values. Once this occurs, it is far more expensive (and I mean add a few 0’s) to fix than drilling a fully sealed well would have cost in the first place.
Here are my recommendations to well drillers for avoiding unwanted problems with flowing wells:
Numbers 1-5 above notwithstanding, if you are underway drilling a well, and have perhaps gone deeper than anticipated and are drilling through a tight formation such as a clay or a silt, and have not sealed in your well casing, stop drilling and regroup before drilling out the bottom of the clay! Better to stop before hitting more water than needed or bargained for.