Water Well Journal
Issue link: https://read.dmtmag.com/i/557876
Water Well Journal: What types of applications do ASR projects have? Pyne: We have identified 28 different applications of ASR to date, and more are anticipated. The four major applications are seasonal storage, long-term storage, emergency storage, and achieving water supply reliability. Each state tailors ASR to meet its own needs, constraints, and opportunities. Eastern states tend to be more interested in seasonal storage. Western states are also interested in seasonal storage, but are more interested in long-term drought-flood cycles that require storage for several years. Areas with highly vulnerable water supply sources tend to be more interested in emergency storage. Other applications include low flow augmentation to meet environmental goals; maintaining low flows and pressures in water distribution systems; water quality improvement during storage through natural physical, microbial, and geochemical processes; thermal energy storage; and many more. ASR well- fields typically are designed and operated to meet several prioritized goals. Scott: Most ASR projects are municipal, though some are used for manufacturing applications. I have heard of their use in agriculture, but am not familiar with any specific examples. It is my impression that the cost per gallon of stored water is simply not viable for most agricultural operations. Water Well Journal: Are there certain types of communities that use them? Scott: The type of community is not really a factor. The use of ASR is driven by water availability and suitable geology for underground storage. Pyne: Adding an ASR well or wellfield to another water sup- ply option such as desalination, a new surface reservoir, a water treatment plant expansion, or the end of a new, long transmission pipeline increases—and can often double—the reliable, sustained yield and reduce the unit capital costs for the additional water provided. Substantial evapotranspiration losses from surface reser- voirs in many parts of the United States can be reduced by storing a large portion of the water underground, effectively integrating operation of the surface reservoir and the ASR wellfield and capturing a greater portion of the runoff from storm events. ASR solutions are easily adaptable and can be imple- mented one well at a time, if desired, to match steadily in- creasing demands instead of having to finance a huge initial capital investment to meet projected future peak demands. Water Well Journal: I noticed there are a lot of ASR projects in California and only a few in Texas. Why the difference? Pyne: ASR wells are utilized by a wide variety of water users, including small and large urban areas, industries, and agriculture. There are somewhere around 500 to 700 ASR wells operating in the country today, in about 25 different states, and approximately 175 different wellfields. There are many ASR wellfields in some states such as Oregon, Califor- nia, Arizona, Florida, South Carolina, and New Jersey. ASR wellfields are also operational in many other countries around the world. Texas is just emerging from a severe drought and recently passed important ASR legislation that is expected to pave the way for many new ASR wellfields in that state. California is still in a severe drought, and recently passed important groundwater management legislation that will also most likely lead to expanded water storage underground, including ASR wellfields, to provide water supply reliability. Florida is also utilizing ASR for underground storage of drinking water and for recharge of its brackish aquifers with high quality reclaimed water, thereby conserving freshwater and eventually eliminating discharge of treated wastewater through ocean outfalls. Some of the ASR wells in South Car- olina are utilized to deal with saltwater intrusion in coastal areas. Scott: California uses lots of recharge projects to protect water supplies from saltwater intrusion. In coastal areas, when freshwater is mined (pumped at a higher rate than natural recharge), it allows saline water to migrate inland against the lower hydrostatic pressures. Recharge projects are commonly used to create a hydrostatic barrier to saltwater intrusion. That may explain the difference. Water Well Journal: There has been some talk that ASR systems may be the solution to water issues in flooded and drought areas. Can you expand on this? Pyne: ASR wells vary in depth from about 100 feet to 3000 feet. Deeper, confined, and semi-c onfined aquifers tend to have slower lateral velocities of regional groundwater movement, favoring long-term storage. Most store water in confined and semi-confined aquifers, while some are in unconfined aquifers. Storage aquifers include a full range of consolidated and unconsolidated formations including ASR SYSTEMS from page 27 waterwelljournal.com 28 September 2015 WWJ There are somewhere around 500 to 700 ASR wells operating in the country today, in about 25 different states, and approximately 175 different wellfields. R. David G. Pyne, PE Peter Scott