Building, Remodeling, Demolition, and Wells
Many homes, farms, and businesses in Minnesota are now served, or were served in the past, by a well. Private and public wells provide the main source of drinking water for three out of four Minnesotans. Proper location, construction, and maintenance of these wells is important to ensure a safe, reliable source of drinking water. Proper sealing of unused wells (filling unused wells with cement or a special clay) is important to protect public safety and prevent groundwater contamination.
Well Management Program
The Minnesota Department of Health (MDH) receives numerous questions concerning wells, and building, remodeling, or demolition projects. The state has enacted a law, Minnesota Statutes, chapter 103I, and a rule, Minnesota Rules, chapter 4725 (Minnesota Well Code), which contain several requirements that can apply to building, remodeling, or demolition. These requirements are designed to assure adequate and safe access to service or seal the well, prevent accidents or injury, and prevent contamination of the well or groundwater.
Buildings and Wells
At some time in the life of a well, it will likely require maintenance or repair. When the well no longer functions, sealing of the well will be necessary. In order to safely and effectively do this, access to the well is needed. In order to have access, and keep the well safe, a building, building addition, overhang, deck, canopy, or other structure may not be built over, or within 3 feet of any existing well. This requirement not only applies to drilled wells used for drinking, but also to sand-points, unused or abandoned wells which have not been properly sealed, and to wells used for such purposes as monitoring or irrigation.
A well may not be located inside a building unless the building is a well house which meets very specific conditions.
The 3-foot separation distance is designed to allow service equipment to access the well to perform service or well sealing, prevent damage to the structure while servicing the well, prevent injury to persons working on the well, and prevent contamination of the well or groundwater. Wells inside buildings are more likely to be contaminated by spills, flooding, or sewer leaks. Easy access to the well with the right equipment also benefits the well owner in terms of lower costs for service or sealing.
Two questions that are sometimes asked are “Can an addition be built over a well if an access hatch or skylight is built into the roof?” and “Can a variance be obtained?” A hatch or skylight does not provide the same access or safety protection, so an access hatch is not an acceptable alternative. A variance may be granted only in very unusual circumstances where other alternatives do not exist, and where the variance provides equivalent protection and safety.
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Sewers and Other Contamination Sources
Remodeling or building projects may involve the installation of sewers or other sources of contamination.
A minimum separation, or “isolation,” distance must be maintained between a well and a source of contamination to protect the well and the groundwater. The distance applies to the construction of new wells, and to the placement of contamination sources near existing wells.
The well rules require specific isolation distances from contamination sources such as petroleum tanks, chemical storage, and septic systems, including the most common contamination source encountered on building projects - sewers.
A minimum separation of 50 feet must be maintained between a buried sewer and a well. This distance may be reduced to 20 feet if the sewer is constructed of cast iron or plastic pipe meeting the standards of the Well Code and the Minnesota Plumbing Code, and if the sewer has been successfully air-tested. The separation applies to all buried pipes carrying sewage, both outside a building, and under the building floor. The separation applies not only to wells used for providing drinking water, but also to wells used for other purposes, such as irrigation.
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Demolition and Wells
Unsealed unused wells are sometimes discovered during building, remodeling, demolition, or excavation projects.
Care should be taken not to damage a well. Damaged wells can lead to contamination of the well and groundwater. Damaged wells are also difficult and expensive to repair or seal.
Wells may not be buried, bulldozed, or otherwise excavated while doing building projects or demolition.
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Whether your property is in a rural area, or in town, you could have one or more wells which are not in use, and which are not properly sealed. If you live in town and are now connected to city water, there may be one or more wells that were used before city water became available, or there may be a well that was used for watering lawns and gardens.
If you live in the country, there may be unused wells that served current or former houses and buildings, or were used for irrigation or livestock watering.
Wells which are no longer in use, or “abandoned,” can be a potential threat to health, safety, and the environment. As a well ages, the casing may corrode or joints may leak. An unused, unsealed well can provide an open channel to allow surface contaminants, surface water, or improperly disposed wastes to directly reach the groundwater. Large diameter wells can be a safety hazard, especially for children or animals.
Wells which are not in use and not properly sealed, and which do not have a maintenance permit, must be properly sealed by a licensed well contractor. Until a well is properly sealed, a building, addition, deck, or other structure may not be built over the well.
Well sealing is the process of removing pumps or other obstructions from the well, inserting a grout pipe to the bottom of the well, and pumping a special grout mixture to completely fill the well. Well sealing may not be done by a property owner, builder, or any other person not licensed to seal wells.
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The MDH has additional publications available at no cost:
- Home Water Treatment Units
- Well Construction Rules
To order, call 651-201-4600 or 800-383-9808
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Contact the MDH Well Management Section
651-201-4600 or 800-383-9808
Minnesota Department of Health