Water Sources: Intake Structures for Ponds and Streams – Wet Well
Overview
Ponds and streams can serve as sources of water in areas where drilled wells are unlikely to provide adequate water or are too expensive. A wet well is a water collection system with a filtered water pipeline inlet from the stream or pond into a below-ground water storage structure. A pump placed in the wet well sump distributes water through a pipeline to livestock drinking devices. Positioning the wet well alongside a stream rather than in the stream bed protects the pump and inlet from damage during flood events and avoids plugging. A wet well can be a reliable source of water during periods of fluctuating water levels.
Advantages
- Reduced bank erosion.
- Reduced livestock impact on water quality compared to direct access.
- Improved quality of water provided to livestock.
- Pond or stream usefulness extended due to less trampling.
- Reduced pump site maintenance and possibility of increased pump life.
- Performs well throughout a wide range of water levels.
Limitations
- Construction equipment may be necessary for installation.
- Few examples in Kansas to use as references.
- Excavation is required below ground level; rock layers could restrict wet well location.
- Usually requires a pump and power supply.
Design Considerations
A backhoe or excavator is used to construct the wet well by digging a well hole, deeper than the stream or pond, more than 20 feet from the water’s edge. A perforated culvert tube or large diameter well casing is placed in the hole. The casing size is determined by the flow rate of the stream, the desired pumping rate, and the type of pump that will be used. The minimum casing is typically between 6 to 8 inches in diameter. Clean gravel is installed around the base and sides of the casing to fill the hole.
Following construction of the well, the intake line is installed to allow water to flow from the stream or pond into the well. A trench is dug between the bottom of the stream or pond to the well casing. The depth of the trench should be level with or below the bottom of the water source. Coarse sand or river gravel filter media or plastic/PVC pipe is installed in the trench to transport water from the source to the well. A large basin around the well casing filled with a clean, uniform gravel serves as a reservoir for storing water near the casing.
When using gravel filtering media, the life of the media can be extended by installing a filter-fabric barrier between the gravel and the soil layer filling the trench. The filter fabric barrier prevents fines from accumulating in the filter rock and will extend the life of the media.
To reduce future maintenance problems, a pitless adapter can be placed in the side of the casing where the water system line leaves the well casing. Pitless adapters serve as a disconnect between the vertical discharge pipe coming from the pump and the horizontal pipeline going to the supply line and adapters should be located below the frost level.
Once all the lines and/or media are installed, soil on the surface can be replaced and reshaped. Soil can be replaced over and around the wet well. Raising the soil level around the wet well diverts surface water intrusion.
This practice may require permits. Please read the permit section of this handbook. Abandoned water wells should be plugged.
