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Infosheet #2 - Water Wells
Table of Contents
IntroductionThis infosheet provides background to Worksheet #2 of the Environmental Farm Plan Workbook. It outlines Options you could adopt to address problem areas in your operation. In most cases you'll need more information before implementation: please refer to the resource materials listed in the infosheet, and consult OMAFRA Environmental Farm Plan (EFP) Technical Advisors. All Options are classed as Actions or Compensating Factors. Actions address the areas of concern identified, and will change the EFP rating to(3) or Best (4). Compensating Factors are alternatives that will adequately address the concerns, but will not change the rating in the EFP worksheets. At the request of the Ontario Farm Environmental Coalition, consisting of Ontario Federation of Agriculture, Christian Farmers Federation of Ontario, AGCare, and the Ontario Farm Animal Council, the following people contributed to the development of Infosheet #2: Jim Myslik, OMAFRA (Chair) Technical Editing Committee: The following people contributed to the revision (2004) of Infosheet #2: Hugh Simpson, OMAFRA (Co-Chair) Technical Editing Committee: OMAFRA = Ontario Ministry of Agriculture, Food and Rural Affairs | Top of Page | Location of WellIssue: 2-1 Position of water well in relation to potential sources of contaminationGround water often moves underground in the same general direction as the surface water. If ground water is contaminated upslope from your well, the contamination may show up in your well making the water unfit to drink. If contaminated water is allowed to flow close by, or (even worse) to pond near the well, the benefits of position are lost. Ask yourself: is your well downslope from contaminant sources? If yes, will runoff flow close to the well? Is there any chance of ponding around the well? What can you do?Option #1 - ActionMove upslope contaminant sources to location downslope of the well:
Option #2 - ActionMove your well upslope of all potential contaminant sources:
Option #3 - Compensating FactorDirect surface drainage from contaminant sources away from your well:
Option #4 - Compensating FactorFor potential contaminant sources that have proper storage(s) or containment, monitor regularly:
For More Information:
| Top of Page | Issue: 2-2 Distance from well to potential sources of contaminationAn important factor in maintaining good ground water quality is the horizontal distance between your well and the potential contaminant source. Minimum separation distances between your well and potential contaminant sources are specified in Regulation 903 of the Ontario Water Resources Act. These separation distances are actively enforced when a new well is constructed or when a new septic system is installed. Any well constructed after 1984 must have met the minimum separation distance at time of well construction. In general, the potential for your well water to become contaminated, decreases as the distance between the well and the sources of contamination increases. Maintaining as much separation distance as possible between the water well and the potential contaminant source is an excellent best management practice to help protect the quality of water in the well. In general, finer-textured soils slow water movement, allowing more opportunity for filtering and cleaning. Soil type indicates whether additional attention and water testing are warranted. However, a low permeability soil type (clay) doesn't guarantee full protection, just as a high permeability soil type (sand) doesn't necessarily mean that your water is or will be contaminated. Bedrock is often fractured. Exposed bedrock or shallow soil depths over bedrock/water table offer very little or no protection. What can you do?Option #1 - ActionMove your well to a distance that achieves a (3) EFP distance rating:
Option #2 - Compensating FactorIdentify the potential contaminant source(s) that is too close (EFP distance rating of 1 or 2) and deal with the Actions in the individual Infosheets related to those contaminant source(s) identified. For More Information:
| Top of Page | Condition of WellIssue: 2-3 Condition of casingA visual inspection of the well casing, and well vent should be part of your annual well maintenance program. The purpose of the well casing is to provide a safe pathway to access an underground water source. It must be installed and sealed carefully so that the well does not act as a link between surface water and ground water sources or for water to move from one ground water source to another. Water is supposed to enter the casing from the bottom. If your visual inspection tells you water is entering through the sides, this means water isn't following the natural flow path and could be contaminated. This can pose a health risk to you and possibly contaminate the aquifer from which the drinking water originates. It's easier to visually inspect a bored or dug well than a drilled well. What can you do?Option #1 - ActionInspect well casing at least once every 2 years and repair any problems or replace any faulty materials as required.
Option #2 - Compensating FactorProperly abandon existing well and replace with new well
Note:Ontario Regulation 903 under the Ontario Water Resources Act specifies that a new well that is dry, or an existing well that is not being used or is not maintained to minimum standards, must be abandoned according to the specifications set out in the Regulation. For More Information:
| Top of Page | Issue: 2-4Condition of well capA visual inspection of the well cap should be part of your annual well maintenance program. The well cap is intended to keep rainfall, surface water, and undesirable materials from directly entering the well. For large diameter wells (i.e., bored and dug), safety can be an issue. People or children can walk or climb onto the well cap so it is necessary to be strong enough to support them. In the case of children, the cap should be secure or heavy enough that the cap cannot be removed by them. What can you do?Option #1 - ActionRepair any problems or replace any faulty materials as required.
Bored or dug wells
Drilled wells
Option #2 - ActionIf cap is missing, install a proper (commercially manufactured and vermin proof) cap. Option #3 - Compensating FactorProperly abandon existing well and replace with new well.
For More Information:
| Top of Page | Issue: 2-5Condition of well ventingA visual inspection of the well vent should be part of your annual well maintenance program. The well vent allows potentially dangerous and explosive gases (e.g., methane) to escape the well. Well vents must be screened or protected to prevent undesirable materials, insects, and small animals from entering the well through the vent. What can you do?Option - ActionInstall appropriate vent and screening.
Bored or dug wells
Drilled wells
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| Top of Page | Issue: 2-6Condition of surface material around the well casingWater well sealing materials fill the space between the drill borehole or excavation wall and the well casing. Their purpose is to prevent surface water or shallow ground waters from seeping directly into the well and to prevent them from seeping into deeper ground water supplies along the casing. If the well seal fails to prevent this seepage then your well and other wells can become contaminated. In almost all cases, settling or cracking of water well sealing materials results from the use of improper materials or the improper placement of these materials. What can you do?Option #1 - ActionConsult a licensed water well contractor for advice on what to do. Option #2 - ActionCarefully excavate the area surrounding the casing and backfill with an approved sealing material to the ground surface:
For More Information:
| Top of Page | Issue: 2-7 Casing depthThe deeper the water source for the well, the more opportunity there is for soil to naturally filter and clean the water before it's used. Drilled wells have a watertight casing (usually steel) that sometimes extends to the bottom of the well and in other situations only part way down (i.e., to bedrock). The depth to which the watertight casing extends is an indicator of the minimum distance that water has to travel through the soil before it can enter the well and then be used. There are exceptions though (e.g., artesian flowing wells, etc.) Bored and dug wells use large-diameter concrete or steel casing, which are harder to make watertight. And although the water generally enters the well from the bottom, it can sometimes enter through the sides if the casing joints are not sealed properly. Note: Do not adjust your rating for naturally occurring water quality problems, such as salty water and sulphur. What can you do?Option #1 - ActionExtend casing of drilled wells to a depth greater than 30 metres (100 feet):
Option #2 - Compensating FactorEnsure that depth of casing meets minimum requirement for type of well and soil profile and monitor water quality regularly.
For More Information:
| Top of Page | Issue: 2-8 Casing height above ground levelYour well can be a direct pathway from the ground surface to the ground water source. If contaminated surface water enters the well through the top, water quality in the well and aquifer are in jeopardy. The well casing must extend high enough above ground to prevent surface water entering the well in the event of flooding or ponding around the well. Regulation 903 of the Ontario Water Resources Act specifies casing height. What can you do?Option #1 - ActionExtend casing of bored, dug, sandpoint or drilled well to 40 cm (16 inches) or higher above the surrounding ground surface.
Option #2 - ActionFor drilled wells in a well pit, extend the casing to a minimum of 40 cm (16 inches) above the surrounding ground surface and properly fill in pit.
Option #3 - Compensating FactorFor drilled wells in a well pit, extend the casing to a minimum of 40 cm (16 inches) above the floor of the pit, and ensure that the well vent pipe extends 40 cm (16 inches) above the surrounding ground surface. The drilled well cap must be water tight (sanitary seal) and the well pit should be sealed or continuously drained.
For More Information:
| Top of Page | Issue: 2-9Age of wellYour well's age is an indicator of the technology used in its construction, and the casing and cap. The well casing may be sufficiently deteriorated to allow water to enter the well near the surface. Some dug wells were built a century ago, when walls were built from stones and bricks. Old wells constructed in this manner are very susceptible to contamination from surface sources of pollution because the joints between the stones or bricks were usually never sealed. What can you do?Option #1 - ActionReplace the old well with a new well
Note:Remember that the old well being replaced must be abandoned according to Ontario Regulation 903 if it is no longer to be used or you do not intend to maintain it to minimum standards. Option #2 - Compensating FactorUpgrade well to present day standards.
Option #3 - Compensating FactorCarefully inspect condition of water well, especially for deterioration of casing.
For More Information:
| Top of Page | Issue: 2-10Type of wellIn general, all types of wells, provided that they are constructed to accepted standards, can provide a safe and reliable supply of water. The depth, quantity, and quality of ground water in your area often dictates what type of well you may have. Drilled wells often provide more protection from surface sources of pollution because they can be drilled to greater depths and are easier to seal than are dug or bored wells. Drilled wells are generally more dependable in both quantity and quality. Bored or dug wells obtain water from a shallower source, which is more easily affected by surface activities and rainfall. The larger bore hole and casing are more difficult to seal and maintain. Any deep hole drilled or dug into the ground provides a potential path for contaminants to reach the ground water, and must be managed accordingly. All four well types must be constructed in accordance with Regulation 903 of the Ontario Water Resources Act. What can you do?Option #1 - ActionWhen replacing a bored/dug or sandpoint water well consider a drilled well where feasible
Option #2 - Compensating FactorProperly manage, maintain, and protect the water well (regardless of type) as outlined in the infosheet. Test water quality at least three times per year. For More Information:
| Top of Page | Management of Water SupplyIssue: 2-11Backflow preventionThe well and plumbing system is designed to bring clean water to the surface. If you don't take precautions, it can also conduct liquids in the opposite direction. Water from the tap or hose is used to fill large and small containers that may have potential contaminants in them, such as sprays, soaps, fertilizers, etc. These can back into the plumbing system or well, endangering human health. Costs for cleanup can be very high. The foot valve associated with pumps in wells does not provide adequate protection against backflow of possible contaminants into the well. Although it can prevent material from getting into the well if it is functioning properly, contaminants can still be siphoned into the water lines. What can you do?Option - ActionInstall anti-backflow devices on all outside faucets, or faucets that are used to fill containers with a hose and maintain a 15 cm (6-inch) air gap between liquid level and hose end.
Types of anti-backflow devices
For More Information:Best Management Practices Books: Water Wells, Order No. BMP 12, page 65; Water Management, Order No. BMP 07, page 17 | Top of Page | Issue: 2-12Unused or abandoned wellsUnused and improperly abandoned wells are pathways for contaminants to move into ground water. These wells must be identified and maintained, or properly plugged (abandoned according to Ontario Regulation 903). If improperly filled in, they may need to be dug up and plugged properly. If you are currently using a particular well for livestock or emergency purposes only, you must still maintain it. When a water well is abandoned (plugged properly), a report should be sent to the Ontario Ministry of the Environment indicating location of water well, type of well, and details of plugging. What can you do?Option #1 - ActionIf an unused water well is to remain in place, it must be maintained and managed.
Option #2 - ActionProperly, abandon the well(s) according to Ontario Regulation 903.
Note: Previously abandoned wells should be investigated to determine if they were properly plugged. A licensed water well contractor can assist you. For More Information:
| Top of Page | Issue: 2-13Water testingContaminated water is often very difficult to identify with our senses. Regular testing will indicate if any changes in water quality are occurring. Results will also indicate what treatment methods are warranted, and why. What can you do?Option - ActionTest water for indicator bacteria at least three times a year, and once a year for other parameters (such as nitrate)
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| Top of Page | For more information:Toll Free: 1-877-424-1300 Local: (519) 826-4047 E-mail: ag.info.omafra@ontario.ca |
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