WorldWide Drilling Resource

22 JUNE 2021 WorldWide Drilling Resource ® Environmental Monitoring by Thomas Kwader, Ph.D., P.G. Owner, Qwater Well Developer and WorldWide Drilling Resource ® Hydrogeologist Well Specific Capacity - The Most Important Data to Collect From a New Well, Part 2 of 2 Last month’s article focused on the importance of collect - ing data regarding the development of all newly drilled wells to document a base - line for future comparison of changes in well efficiency. There may be a number o f reasons a well appears to “dry up” or become less efficient, including: 1) The well was drilled during a wet season with unusually high groundwate r levels, which allowed “thicker” water zones to be available before cavitation o f the pump occurs; 2) Lower than “normal” rainfall conditions that do not allow the aquifer to ris e to water levels at the time the well was drilled; 3) If an additional well(s) was installed nearby, the new well(s) could be con - tributing to lowering the water table to historically low levels; and, 4) The plugging of the screen with fine-grained materials and/or bacteria l growth of algae or “slimes” in the well (chemical treatment and/or redevelop - ment may fix this problem). In last month’s article, the importance of collecting information on the Specifi c Capacity of the new well was discussed. Specific Capacity (SC) is the amount o f drawdown the water level in the well at a given pumping rate, expressed as: gp m (gallons per minute) pumped divided by the amount of drawdown in the well in fee t (ft) or: SC = gpm/ft, (when the water level stabilizes) If the original Specific Capacity of the well is known, then the reason for th e well “going dry” can be narrowed to either being a “well plugging problem” or du e to declining water levels in the area. If water levels are declining over time, the fix to obtain more water may includ e lowering the pump, pumping at a lower rate (but pumping more hours per day t o maintain a steady flow rate), or to drill a deeper new well farther away from the existing wells. If water levels are not showing declines in the area, the well may need to be chemically treated and/or physically redeveloped (surged and pumped hard) to reopen the “flow paths” near the borehole. Tom TomKwader may be contacted via e-mail 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 ENV LOOK!!! Our Mailbox is overflowing with letters from happy readers! Here are just a couple! Your magazine is really great. Thank you, and keep up the good work. Paul Cedar Falls, IA Great resource! Thank you. New Subscriber in Exeter, CA