Close up of a well screen/Photo credited to the NGWA
Well screens are typically attached to the bottom of the well casing. They allow water to move through while preventing sand and gravel from entering the well. They are used on wells located in a sand and gravel aquifers.
It helps to maintain the flow of water into the well and protects the pump from damage caused by silt and sand. The screen is an important component of a well and its proper sizing and installation are crucial for optimizing well yield.
What is a gravel pack?
A gravel pack, or filter pack, serves as a protective layer of sand or gravel positioned outside the well screen, situated between the screen and the borehole wall . Its primary function to prevent fine sediment from infiltrating the screen.
Typically composed of coarse sand or gravel, the gravel pack is carefully selected based on the grain size of the aquifer’s sand and gravel particles . By allowing water to flow through while blocking sand and gravel, the gravel pack works in tandem with the well screen to ensure the efficient and effective operation of the well.
What size of well screen does my well need?
The screen openings, or slot size, are selected based on the size of the sand or gravel particles in the aquifer. These slot sizes are measured in hundredths of an inch. The screen is usually made of materials such as stainless steel, carbon steel, plastic, or brass. It is typically 3 to 5 feet in length for residential wells but can be longer for municipal, industrial, or irrigation wells.
Choosing the right screen size is critical to prevent sand from being pumped, which could harm the pipes and pump system. Consult with a professional water well installer who can determine the well screen slot size and length needed.
Can my well screen corrode?
Yes, water with low pH can potentially cause corrosion on your well screen. The acidity of the water can lead to the corrosion of pipes, faucets, and hot water heaters over time. This corrosion can result in the presence of copper and lead in your water if you have copper pipes with lead solder. It is important to keep an eye on the pH level of your water to prevent corrosion and potential contamination.
How does a well screen get plugged?
A well screen can get plugged due to various factors such as the accumulation of soil, gravel, or other loose debris. This can happen over time as water flows through the screen, carrying particles that eventually settle and clog the openings of the screen.
Additionally, obstructions can occur if there is an off-center or irregularly shaped obstruction in the borehole. It is important to properly maintain and clean well screens to prevent plugging and ensure the efficient flow of water.
What do I do if my well screen gets plugged?
If your well screen gets plugged, it is important to address it promptly to ensure the proper functioning of your well and to prevent any potential contamination issues. The type of the obstruction will determine what technique will be used to clear it.
Soft obstructions: If the obstruction is soft, such as soil, gravel, or loose debris, you can try using an air or water jetting/surging line along with a compressor to remove it. This method can also be used for removing bentonite chips or slurries.
Hard obstructions: If the obstruction is hard and cannot be removed using the jetting/surging method, you may need to consider other techniques. The specific method will depend on factors such as the depth of the obstruction, its location in the well, and the shape of its upward-facing surface.
If you are unable to remove the obstruction on your own or if you are unsure about the best course of action, it is recommended to seek help from a professional well drilling contractor. They have the expertise and specialized equipment to handle well screen obstructions effectively.
What steps can be done to determine what is plugging my well screen?
If you are unable to remove the obstruction on your own or if you are unsure about the best course of action, it is recommended to seek help from a professional well drilling contractor. They have the expertise and specialized equipment to handle well screen obstructions effectively.
Visually inspect for an obstruction: Visually inspect the screen and casing for any visible signs of clogging or blockage.
Conduct a water flow test: Run water through the well and observe the flow rate. If it is significantly lower than expected, there may be an obstruction.
Inspect with a well camera: Perform an inspection with a well camera, a specialized tool that allows you to examine the inside of the well. It can provide a view of any blockages or buildup.
Remove the pump: It may be necessary to remove the pump to access the well screen. This can be done by hiring a professional well contractor who has the expertise and equipment to safely remove the pump.
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