WorldWide Drilling Resource

13 MAY 2021 WorldWide Drilling Resource ® WWDR photo. After more than 42 years in the drilling industry, Rob Caho, director of sales and marketing for Diedrich Drill, announced his retirement. The company stated, “ We are indebted to Rob’s service and will certainly miss him. Rob has been an integral part of the Diedrich Drill family during his tenure. Rob’s contributions, hard work, and dedication throughout his 42- year career in the drilling industry are worthy of emulation and admira- tion. Join us in wishing Rob happiness, health, and prosperity as he moves forward to enjoy a well-earned retirement.” Congratulations on Your Retirement, Rob! Environmental Monitoring by Thomas Kwader, Ph.D., P.G. Owner, Qwater Well Developer and WorldWide Drilling Resource ® Hydrogeologist Specific Capacity - A Measure of the Health and Efficiency of a Well, Part 1 of 2 Well Specific Capacity is a measurement of how much water a well can produce at a given pumping rate. For example, if a well is pumping 50 gallons per minute (gpm) and draws down (dd) 10 feet, the well’s specific capacity (SC) is said to be: [5 gpm per foot of drawdown or SC = 5 gpm per ft: dd] The higher the specific capacity, the more efficient the well. Specific capacity should be measured after the pumping water level reaches a relatively constant depth in the well, while maintaining a constant pumping rate. A valve located on the discharge side of the pump may be needed to adjust the flow to maintain a constant water level. If additional flow is desired from the well, the specific capacity of the well can be useful to calculate the size of the pump necessary to obtain the maximum pumping rate the well can sustain. Some wells will reach a “stable” water level in a few minutes, while other wells may continue to draw down for an hour or more. If the well continues to draw down for a long time, this indicates the cone of depression is growing to increase the size and slope of the cone of depression (or funnel) to supply water to the well. I have seen screened wells pumping at one gpm drawdown continuously until the 50- foot-deep well went dry; and I have seen fractured rock wells stabilize with less than one foot of drawdown in less than one minute, while pumping in excess of 1000 gpm. These are reasons why a pump test is highly recommended on a new well to determine the optimum size of the pump needed to obtain the maximum pump efficiency. Be sure to confirm, before any specific capacity test is conducted, that the well is fully developed to remove all drilling mud and formation “fines” in and around the bore- hole. Thorough well development is necessary on all newly drilled wells before specific capacity data is collected. If a new well is not producing much water and continues to draw down significantly for more than 15 minutes, there is a good chance the well is not fully developed. It should also be noted, an undeveloped well will have a lower pumping level which will also require more “lift” and electricity (watts) to operate in the years to come. Well Specific Capacity is the most important measure of a well’s capacity and effi- ciency, and an indicator that if a well begins to cavitate in the future, water levels may have dropped or the well needs to be redeveloped. Tom Tom Kwader may be contacted via e-mail to ENV 302-684-3197 FAX: 302-384-0643 142 Broadkill Rd. • Milton, DE 19968 email: Manufacturers of Slotted & Perforated Pipe ranging from ½” to 24” diameter Atlantic Screen & Mfg., Inc. • Well Rehab. Products • Manholes • Bentonite • Filter Sock • Inline Chemical Mixers • Sampling Bailers • Clear PVC Pipe • Locking Caps