The 6" Stone-packed Shallow Well or "Six-Packed Well"
This document outlines a modern procedure for installing a simple and safe shallow well. By design this system has many advantages over conventional dug wells, from installation through operation and maintenance. It eliminates many of the problems inherent to wells that are built of several tiles or well rings stacked upon each other.
This installation results in somewhat of a cross between a drilled bedrock well and an old fashioned well point. It more closely resembles a gravel pack well installed only by well drilling contractors, but is actually dug with conventional excavation equipment.
The unique design utilizes small diameter solid pipe, usually 6" PVC, that extends from a convenient height above ground down into the water table. This is much the same as the lift pipe for a well point or the casing of a drilled well rather than a stack of several short tiles. The pipe is slotted or perforated at the base to permit the entrance of groundwater. Water storage is accomplished by adding a significant amount of crushed stone around the base of the pipe rather than by using large diameter well tiles. The water line from the well can either be a suction line with a foot valve at the bottom or it can support a deep-well type submersible pump. Water exits the well through a pitless adapter in the side of the casing the same as it does in a drilled well. Above ground, the completed well has the appearance of a drilled well because all that is exposed is the small pipe.
Elimination of contamination: The 6" casing is easily covered with a conventional drilled well cap that seal out insects, animals and debris. Also, because the one-piece well casing pipe extends from the top of the well to far below the frost line, the possibility of surface contamination through joints is eliminated. When frost lifts and separates conventional well tiles from one another they often settle back down slightly out of position, providing a passage for soil, debris, and contamination to enter the well. Frost action has no effect on a one-piece smooth-wall well casing. Rigid PVC pipe provides the additional advantage of durability compared to concrete tiles that can deteriorate over time if poorly manufactured or subject to severe environmental conditions.
Maintenance: Servicing the water supply line in the well is accomplished entirely from the surface rather than requiring entry into the well. A simple pitless tool (a piece of threaded pipe) can reach into the well to lift out the suction line and foot valve, or pressure line and pump if a pump is installed in the well. Although there is little chance of contamination, a suction pump line can easily be lowered down inside the casing to the bottom if the well should need to be cleaned or redeveloped.
NOTE: Several wells of this type were installed in the Conway area during the last 15 years and have been trouble free. Most are about 20 feet deep which was the practical limit of the excavator used to dig them. Some have a foot valve in the well with the pump in the house while others have a submersible pump in the well. The pump in the well eliminates pump noise from the house and also eliminates the need to prime the pump. Whenever a pump is installed in the well, the system is fitted with a low water cutoff switch to protect the pump in times of drought or high water use.
"Six-Packed" shallow well construction details
As with most shallow wells, the stone-packed well is installed into the ground water table by digging a hole as deep as possible with an excavator (usually about 20 feet) and placing 6" to 12" of crushed stone in the bottom. The well casing that has had the bottom 5' or so drilled with 5/8" holes or slotted with a series of short 1/8" saw cuts, is stood up in the hole. The top of the pipe is covered with a clean 5 gallon bucket. Three ropes are tied to the pipe through the handle of the bucket to hold them at the top and secured to trees or equipment stationed safely away from the hole. Ropes are tightened and adjusted to the hold the pipe vertical. The hole is then filled with as much 11/2" crushed stone as possible to provide adequate water storage.* The top of the stone is leveled and completely covered with a layer of geotextile filter fabric.
The pitless adapter should be installed approximately six feet below finish grade for frost protection. If this level is significantly above the top of the crushed stone it is essential to compact the clean granular backfill that is used between the top of the stone and the bottom of the pitless adapter. If not compacted, the soil may settle and pull the supply pipe to the house off of the adapter.
Final backfill should make a transition from clean granular sand and gravel to silts and clays near the surface and sloped away from the well for drainage. As soon as all backfill is in place the well should be pumped out to develop it and wash out any fines in suspension in the water before they settle out. If necessary, the well pipe can easily be extended to a safe distance above grade (18" to 24") by gluing a short piece of 6" casing onto the original.
Summary of "Six-Packed Well" advantages:
- Worker does not have to enter well during construction to set and level base tile. All work is done from the surface of the ground.
- One piece casing reduces possibility of contamination.
- Water service line utilizes a standard pitless adapter that can support either a pump or a foot valve in the well.
- All maintenance is done from the surface.
- Well is tightly sealed without the need for a heavy concrete cover.
* Note that 1 ½" crushed stone is approximately 40% voids and one cubic foot of water equals approximately 7.5 gallons. 40% of 7.5 gallons equals 3 gallons per cubic foot of stone x 27 cubic feet of stone per yard equals 81 gallons of water per cubic yard of stone. 75 gallons of water storage per yard would be a conservative round number for estimating purposes.