69 DECEMBER 2021 WorldWide Drilling Resource® RENEW - SUBSCRIBE NOW! Drilling Professionals - Low-Yielding Water Well Counselors Compiled the Editorial Staff of WorldWide Drilling Resource® Drilling professionals, you have the ability to help your customers who are struggling with low-yield wells. Consider yourself water well counselors, with the knowledge and expertise to restore relationships with their struggling water well. They may just need peak-demand counseling or specific strategies to restore their compatibility with their well. Or it may be the well needs rehabilitation. Usually, there is not a straightforward answer. Upon what does a contractor base the decision to rehabilitate a well? When you get that call, first consider the well’s ground formation. Low-yielding wells are generally considered wells which cannot meet the peak water demand for the home. In these wells, the water pumps out faster than it flows in, eventually resulting in the water falling to a trickle or stopping altogether. Wells completed in highly porous, saturated geologic materials routinely result in high-yielding wells. Those completed in less porous clays and bedrock can slow groundwater flow to less than five gallons per minute. What type of well are you dealing with? Next, talk to the owner about their typical water usage because this does not occur evenly throughout the day. Peak water usage times are usually during the morning and/or evening. These peak demand periods can last from 30 minutes to 2 hours, and most homes have 2, 2-hour peak periods per day. As a rule of thumb, an adequate water system needs to yield enough water to satisfy a peak demand for at least 2 hours at a time. In general, 50-100 gallons per person per day, or 200-400 gallons per day for a family of four, is typical home water use. Make sure their water system is sized to provide the required amount of water in the 2-hour period. When are their peak hours, and how much water do they actually use? Examine the well itself, as well as the pump. Check to make sure the pump and well casing are sized to pump the needed quantities of water. If the submersible pump is too shallow, it can draw down the water level too fast. In that case, the pump goes on and off repeatedly when the water table falls and rises, often damaging the pump. If the elevation of the water table dropped after the well was constructed, this could be why it is failing to yield sufficient water. A short pumping test, checking pump function, flow, water quality, presence of sand, and other factors, can clarify any problems. Sometimes it is just the pump because pumps do wear and clog. WTR Drilling Professionals continued on page 70
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