|Flexible Drop Pipe » Unique Features and Applications » Boreline ApplicationsIntroduction (ASR)
Aquifer Storage and Recovery (ASR) involves collecting water (stormwater, snow melt, etc.) at a time when it is abundant and then transferring it into naturally occurring underground spaces (aquifers) that consist of porous or fractured sediments of rock. The water is stored below ground and is recovered as needed.
Most ASR systems provide seasonal water storage, storing water during the wet season and recovering it later during extended droughts. Increasingly many water managers are constructing ASR systems to ensure reliability during emergencies, whether severe floods, earthquakes, contamination incidents, pipeline breaks, or potential damage due to warfare or sabotage.
Issues to consider are that the water resource must be abundant, plus there has to be a system for collecting it. The aquifer must be able to receive and deliver water at rates that are consistent with the projected use.
Natural water quality in the storage zone ranges from fresh, suitable for drinking without treatment, to brackish, including total dissolved solids. Most sites have one or more natural water quality constituents that are unsuitable for direct potable use except following treatment. Such constituents may include elements which are typically displaced by the stored water as the bubble is formed underground.
ASR provides a cost-effective solution to many of the world's water management needs, storing water during times of floods or when water quality is good, and recovering it later during times of drought or when water quality from the source may be poor. By storing water in underground aquifers, one reduces or eliminates the need to construct large and expensive surface reservoirs. Due to long term over pumping of groundwater, levels can now be restored as water is recharged.
The main driving force behind the current rapid implementation of ASR technology around the world is water supply economics. ASR systems can usually meet water management needs at less than half the capital cost of other water supply alternatives. It is also important to note that by reducing or eliminating the need for construction of dams, and by providing reliable water supplies through diversions of flood flows instead of low flows, ASR systems are usually considered to be environmentally friendly.
Water is stored deep underground in water-bearing geologic formations, or "Aquifers" that may be in sand, clayey sand, sandstone, gravel, limestone, dolomite, glacial drift, basalt and other types of geologic settings.
Most operating ASR sites are storing treated drinking water. When recovered from storage, this water usually requires only disinfection before being sent out to the water distribution system. Treated wastewater is reclaimed and piped to golf courses, parks, gardens and other areas requiring irrigation to reduce the demand for potable water.
When rains begin and irrigation demand ceases, reclaimed water is stored in ASR wells in deep brackish aquifers, from which it is recovered when needed to meet irrigation demand during dry periods.
Several sites are storing untreated groundwater pumped from overlying or underlying aquifers, or from wellfields located at great distances from the ASR site. When needed, this water is recovered from the storage zone and combined with whatever flows are then available from the primary water sources, to help meet peak or emergency water demands.
Groundwater is increasingly viewed as a desirable application of ASR technology. The newest ASR application is for storage of partially treated surface water. Stored water is recovered to help meet peak demands for supplemental untreated water, whether for urban needs, ecosystem protection, low streamflow maintenance, agricultural irrigation, industrial water requirements, power plant cooling make-up water, or other needs.