aquifer storage and recovery

What is ASR?

Aquifer storage and recovery (ASR) is an effective water management tool to help meet current and future peak demands for high quality drinking water. Essentially, ASR involves storing drinking water underground and then pumping it out when it is needed.

How does ASR work?

Typically, ASR involves injecting treated drinking water from a water treatment plant into natural underground formations (aquifers) during the wet season, when water is plentiful. Stored water is pumped out of the aquifer during the dry season when demand increases as water customers drink more water and use it for outdoor activities, primarily as irrigation for landscaping and gardens, washing cars, and cleaning paved surfaces. Specialized water wells typically are used to inject and recover the treated drinking water.

How much water can be stored in an aquifer?

Aquifers are a geologic formation, or group of formations, that are porous enough to hold water. Usually, aquifers have much larger storage capacity than aboveground municipal storage tanks. For example, 150 million gallons of storage is the goal for ASR, while the typical capacity of a municipal storage tank ranges from 1 to 20 million gallons. To give you some perspective: in the United States, each person uses an average of 70 gallons of water per day. Assuming four-person households, 150 million gallons would supply a city of 50,000 people with enough water for about 11 days.

Is the water safe to drink after it is pumped from the aquifer?

Yes, it is. Treated drinking water is pumped into the aquifer for storage. To ensure that the stored water is safe to drink, rigorous water quality testing and data collection are performed so that water from the ASR wells meets the high state and federal water quality standards. For example, it must meet the U.S. Environmental Protection Agency’s maximum contaminant levels for trace elements, and different types of organic and microbial (biological) contaminants.

Where is ASR used?

The first ASR project in the United States was in New Jersey in 1969. ASR wells now are operating in at least 16 states and in several other countries. In the Pacific Northwest, there are numerous ASR projects. GSI staff members, who were instrumental in bringing this management tool to the region, have worked on more than 20 ASR feasibility studies, most of which have been conducted in basalt aquifers. And we are assisting public and private clients with six ASR projects that are in operational mode—water is being stored, recovered, and delivered. Some of these projects have been operational for more than 10 years.

What are the benefits of ASR?

• Each ASR well acts as a vast underground drinking water storage facility.
• Cost to store water using ASR can be 100 times less expensive than building new aboveground storage reservoirs.
• ASR can help meet future water demands, as well as postpone or limit the need to purchase water from other sources.
• ASR can help a municipality postpone building new aboveground storage reservoirs and larger transmission pipelines, which are more expensive than ASR.
• Recovered water from an ASR facility is often cooler in the summer than water from primary surface water sources, which is an added benefit to summertime users.
• ASR does not deplete the native groundwater resource and it helps to keep streamflows higher during the dry season, which benefits fish and other aquatic species.
• Stored water is an excellent backup emergency supply in case of an interruption in the primary water supply.
• ASR systems are considered to be more environmentally friendly than surface reservoirs. They also offer more protection from tampering.
• The typical winter-spring ASR storage period also avoids inherent losses caused by evaporation that occurs in reservoirs.
• Less water is removed from primary river sources in the summer when using ASR, which is beneficial to fish and other aquatic life.
• ASR may restore and expand the function of an aquifer that has experienced long-term declines in water levels as a result of heavy pumping necessary to meet growing urban and agricultural water needs.

Where can I get more information about ASR?

For additional information about ASR, click here for a link to the Aquifer Storage Recovery Forum.

You also can contact us at (503) 239-8799 or at info@gsiwatersolutions.com.