Water Well Journal
Issue link: https://read.dmtmag.com/i/557876
enough diameter to accommodate the well casing and also provide for installa- tion of filter pack sand in the annulus outside the well casing. The cementing of the intermediate casing can be accomplished by either pumping the cement directly into place through a tremie pipe in the annulus, or by pressure grouting the cement, using a float shoe or Braden head. All these considerations can drive up the cost of the intermediate casing installation, but those costs will be recovered many times over during future years of well operation since well replacement be- comes relatively simple and the expense of land acquisition for new well sites will be avoided. Once the intermediate casing has been installed and cemented in place, the well casing and screen can be in- stalled and hung in tension from a steel plate at the land surface, between the well casing and the intermediate casing. After filter pack sand is installed around the well screen, the well can then be developed and operated. After the initial well has been in use for numerous years, it can be replaced to address changes in the water table, groundwater quality, water system demands, or just wear and tear on the well casing and screen. After the steel plate at the land sur- face is removed, the well casing and screen can be pulled out of the well (the filter pack sand may need to be removed before the casing is pulled, which can be readily achieved). A replacement well (possibly with a different screened inter- val or other changes in the well design) can then be reinstalled, and the modified well can be redeveloped for continued use. The modified well (within the origi- nal intermediate casing) is constructed of new materials and improved design attributes, which are consistent with the current hydrogeologic environment around the well. Although climate change and peri- odic drought conditions should be ad- dressed by well designers, the fact of the matter is future conditions are uncertain. Therefore, the most prudent approach to meeting the uncertainties in the future is to incorporate flexibility into today's designs for water supply wells. A flexible well design may increase the well construction cost in the short term. But in the long run, it will result in significant cost savings (in some cases, millions of dollars over the life of the well) by increasing the well's opera- tional efficiency, reliability, and longevity. WWJ Figure 4. Well designed with an intermedi- ate casing to provide flexibility in the fu- ture. Twitter @WaterWellJournl Marvin Glotfelty, RG, is co-founder and prin- cipal hydrogeologist with Clear Creek Associ- ates in Scottsdale, Arizona, and has been involved with the design, installation, rehabili- tation, or abandonment of more than 800 water wells in the southwestern United States. He was the 2012 National Ground Water Research and Educational Foundation William A. McEllhiney Distinguished Lecturer. Donald Hanson, RG , is a principal of Clear Creek Associates and a recognized expert in water resources projects as well as environ- mental investigation and remediation. CALL AIR PUMP WATER SOLUTIONS INC. 1-877-423-7629 OR VISIT AIR-PUMP.COM How can you take care of iron and sulfur problems and remain competitive? It's a breeze! The Breeze Aeration System is a superior alternative to expensive packaged systems. Air volume and pump activation is controlled with a simple digital timer, significantly reducing cost and improving performance. All components available to customize & simplify your install. The Breeze — Aeration Made Simpler! • No Pressure Switch Wiring • No Flow Switch • No Over or Under-Aerating • No Leaky Vents • Outstanding Value Installation is a Breeze! Reliable Performance! for sulfur and iron problems Bre TM WWJ September 2015 19