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Photograph of  a loose, unsanitary well plumbing system exposed to surface water runoffr  © DJ FriedmanHow to Abandon a Well
Procedures for decommissioning a drilled well, bore hole, or dug well safely

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How to decommission or abandon a water well:

We include recommendations for abandoning a drilled water well or borehole that will no longer be used and we provide research citations on proper well sealing or abandonment procedures.

In a second discussion we describe the procedure for abandoning a dug well.

The article includes research and regulation citations on water well or bore hole abandonment or decommissioning and adds warnings about practical problems that may occur during well abandonment.



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Well Abandonment / Bore-hole Sealing Procedures for Wells Taken out of Service

Old wells, lots of things to fix (C) Daniel Friedman Photograph of a dug well interior

[Click to enlarge any image]

The steps you need to take to seal off a water well or to de-commission a well depend on

Reader Question: how to shut down a well - how to abandon a well

Photograph of a water well pit(May 3, 2012) Mark said:
whats the best way to shut down a well. I mean to fill it with sand or concrete. ?

Reply: Abandoning a drilled well, bore hole, with steel casing

To *properly* abandon a drilled water well or bore hole well (such as a well with a steel casing) usually means

  1. Remove the well piping, pump, wiring, etc. from the well casing.
  2. Divert surface runoff away from the well.
  3. Disinfect the well? Hire a Pro? Depending on regulations where you live you may be required to disinfect the well and also to hire a professional. The example comment below is excerpted from Washington State's DOE instructions in the U.S. A.

    You will need to contact a licensed well driller to decommission a well. Washington law requires all wells be decommissioned by a licensed driller. A licensed driller will have experience with well construction and decommissioning materials and methods. They also know about the local geology. All of this knowledge is necessary to safely and properly close a well.

    Costs to decommission wells will vary depending on the depth, diameter , and geology of the area. Special equipment may be required to remove old pumps and pipes from the well. You will need to send in a “Notice of Intent to Decommission a Well” to the Department of Ecology at least 72 hours in advance of the work.
    - Washington State DOE, retrieved 31 Jan 2015 original source: https://fortress.wa.gov/ecy/publications/publications/96br097.pdf

    Watch out: the amount of bleach actually needed to disinfect a well depends on the actual volume of water in th well - which is a function of the well water total depth and well diameter.
    See WELL CHLORINATION SHOCKING PROCEDURE
    and
    See STATIC HEAD, WELL DEFINITION - how to calculate the amount of water in a well.
    A general guide using laundry bleach (5.25% chlorine) is to use 3 cups of bleach per 100 gallons of well water. If you are using hypochlorite granules (70% chlorine) you can use 2 heaping table spoons per 100 gallons of well water, pre-mixed and then poured into the well, washing down casing sides in the process. Also take care that handling bleach itself is dangerous and requries appropriate caution and protective gear.
  4. Seal the well to be abandoned. There may be alternative methods that are acceptable depending on local regulations, well depth, casing condition, etc. such as using a plug in the casing for deep wells but there are concerns with plug failure: analyzed by Mainguy (2007) and Jiminez (2002).

    Generally the well company will fill in the well with concrete to be sure that surface water or casing leaks never inject contaminants into the aquifer via the well bore. Don't use sand as that won't prevent surface runofff or other contaminants from entering the well.

    Well plugging materials commonly used include "neat cement" (6 gallons of water per 94 pond bag of cement), bentonite clay slurry used for commercial grouting or plugging bentonite, or pelletized or crushed bentonite: pellets or chips of bentonite clay that will swell (to 10x original volume) when wet. If using bentonite chips use larger coarse product (3/8 to 3/4 ") that will pour well into the well casing.

    For a 6-inch well casing you'll need about 15 pounds of coarse bentonite clay filler per foot of well depth.

    Watch out: if your well plugging material is not successfully poured to the bottom of the well you may be required to bore out the whole mess and do the job over again. Pour materials slowly and be sure they are falling to the well bottom.

    Some juridictions require that the well casing top of a decommissioned well should be welded in place or sealed by a threaded or mechanically attached water-tight cap.
  5. Cut off the casing? Some jurisdictions require that after shocking and sealing the well the casing shoudl be cut off and then capped below ground, typically at 2 feet. The hole or well pit if a well-pit is involved, is then back-filled.
  6. Record the well location (opinion)
  7. Report the well decommissioning as required by local codes.

Abandoning a Hand Dug Well

Dug well abandonment details - adapted from Kansas DOH http://www.kdheks.gov/waterwell/download/PluggingHandDugWellsFactSheet.pdfHand dug wells (and large bore hole wells) present both the risk of contamination of the aquifer by surface runoff and the risk of personal hazard should someone fall into the well.

Dug wells, too, if not to be used, should be safely and properly abandoned. However depending on its original construction (such as dry stone laid well wall) it may be difficult to assure that surface water won't run into the well excavation.

The following dug well abandonment advice is adapted from the Kansas Department of Public Health in the U.S. Check with your local government as other regulations may apply at your location.

  1. Find the high water level: Measure the water level in the well with a weighted tape measure or string. If marks in the well indicate that water levels have been higher than present, use the higher water level.
    See WELL DEPTH, HOW TO MEASURE
  2. Disinfect the well: Pour approximately two gallons of chlorine bleach into the well to properly disinfect it.

    Watch out: this DOH advice is not entirely reliable as the amount of bleach actually needed to disinfect a well depends on the actual volume of water in th well - which is a function of the well water total depth and well diameter.
    See WELL CHLORINATION SHOCKING PROCEDURE
    and
    See STATIC HEAD, WELL DEFINITION - how to calculate the amount of water in a well
  3. Knock down the top five feet of the well wall material and let it fall inside the well.
  4. Fill the well with sand and gravel to the water level top which was measured in Step 1 above (the blue line in our sketch). Use the weighted string or tape measure to determine when enough san and gravel have been added.
  5. Fill in the remaining open space with compacted natural clay or approved grout to a depth of 5 feet below ground surface.
  6. Use approved cement or sodium bentonite and sodium bentonite grouting material to fill the well from 5 feet to 4½ feet below ground surface.

    Watch out: if the well excavation at the end of this step is a fall-in hazard to anyone and considering that in step 7 we are to wait for the bentonite to cure, it may be necessary to set up appropriate guards or barriers to prevent an accident. Washington State's DOE reported:
    There have been no reported deaths of people falling into abandoned wells in recent years in Washington state but just about every year there are reports of dogs, horses or other farm animals injured or killed from a fall into an abandoned well. In August 2012, a 1,800-pound horse fell into an abandoned well in Centralia and died after a rescue attempt by local firefighters. The horse had stepped on top of a concrete lid that covered the top of the well, which collapsed underneath the horse’s weight. In July 2012, a 13-year-old pet draft horse fell through a covering on an abandoned well near Shelton but was able to keep his head above water until fire department rescuers were able to pump the water from the well and pull him free. Dogs have died or have been injured in recent years on Vashon Island and near Chehalis. Photo of worker climbing down an abandowned well. Courtesy of Riverside Fire Authority Note that abandoned wells cannot be used for animal carcass disposal. - retrieved 31 Jan 2015 original source: http://www.ecy.wa.gov/programs/wr/wells/abandon-wells.html
  7. Backfill the remaining well depth: after a proper amount of time to allow for the curing of the grouting material, back fill the remaining part of the well with surface soils all the way to the surface.
  8. Report the plugging of the well as required by your local authorities. For example Kansas requires a plugging record to be filed with the KDHE Bureau of Water - Geology Section.

References & research on proper well abandonment procedures

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