Geological Survey Program

Wellhead Protection Section

Monitoring Wells

Monitoring wells are constructed to obtain site-specific water quality, contaminant movement or hydrologic data from proposed or existing sites that may impact groundwater quality.  This requires their construction to be different from other types of wells.  The majority of the other types of wells in Missouri use what is referred to as open-hole construction.  Open hole construction fully exposes rock formations in the borehole of the well, below the well’s casing. 

Monitoring wells constructed in Missouri use a full-length construction.  In most cases, this means a screen in the shape of a pipe is connected to a solid-walled pipe, called a riser, both of which are installed in the open borehole.  The screen is then surrounded by a filter material and the riser is sealed in place using one of several forms of sodium bentonite, or a cement and bentonite mixture.

Missouri sets the minimum construction standards for many types of monitoring wells.  Lysimeters, injection and extraction wells, direct push or small diameter wells, soil vapor probes and piezometer wells are all examples of monitoring wells regulated under the Missouri Well Construction Rules. 

All monitoring wells at least 10 feet deep and left in place more than 30 days must be reported. All monitoring wells at least 10 feet deep must be properly plugged and reported regardless of the length of time the wells were in service.   Monitoring wells less than 10 feet deep are exempt from reporting rules or construction standards.  However, as with all monitoring wells, those less than 10 feet deep must be plugged when their use is no longer required.          

We offer a number of services that may be helpful in working with monitoring wells in Missouri.  These services include: