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New shallow well runs out of water
I'm located in Charleston, South Carolina and installed shallow well system. 3" casing at 22' and 1 1/4" suction pipe with foot valve at 20'. Water level in casing 9' level. Problem is pump and pressure great but after 1min. pump runs out of water and takes about 2min. to recover. Question: Should the casing have holes in it to allow water in from all levels? Soil sandy with clay mix.
How many GPM is the pump pulling? If you choke back the pump, how many GPM can the well produce? 11 feet is not a lot of storage and the cone of depression may vary depending on soil condition.
Why did you stop at 22 feet? What are the soil layers up to that depth? Slotted (screen) casing could let in more water initially but if the cone of depression drops, it would not last. It sounds like the well needs to be developed to increase recovery.
If at all possible, I like to see the footvalve on a shallow well set at about 30 feet, so that the recovery rate of the well cannot be out-pumped. Esentially, the pump will self-regulate the GPM as the level drops.
The 11 feet of head gives you less than 4 gallons of storage, so a pump that moves more GPM than the well can recover will undoubtedly suck air in no time.
The 1 hp pump is designed for 26' max lift and with the external piping to pump I'm within 7'' of max. The soil is sand to about 8' the 1' of clay then sand. What do you mean by: well needs to be developed to increase recovery? Should I increase casing size with a slotted casing?
THANK YOU
Was the well drilled by a licensed professional or was it a DIY job? If done by a pro, was there a well report that indicates what GPM the well can produce?
Again, at the risk of sounding repetitive, why did you stop at 22 feet? Unless you hit bedrock or unfavorable material, you should go deeper. The intake really should be lower than what the pump can lift so that it won't suck air.
Developing the well involves opening up the aquifer to allow more GPM of flow. There are several methods used to develop a well and a search of this board will reveal a few links I've posted. Over-pumping the well is probably the most popular DIY method but with a marginally producing well with just 11 feet of draw, it may not yield results. When you are pumping, is there still turbidity or is it running clear? Sometimes, reversing the flow is needed to shake up the aquifer a bit so that more fines can be removed.
I recently remediated my 13 year old well so that I could increase the GPM of production. At the start, the submersible pump would suck the well dry if ran unchecked, but since it never ran clear, I persisted until I could increase the flow to full bore and until it ran clear. Now the pump cannot suck the well dry even if run continuous and there is no turbidity.
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