Artificial Groundwater Recharge/Aquifer Storage and Recovery. CEAM Annual Meeting January 30, 2014

Transcription

1 Artificial Groundwater Recharge/Aquifer Storage and Recovery CEAM Annual Meeting January 30, 2014 John Greer, PG Barr Engineering Co.

2 what will be covered artificial groundwater recharge (AR) and aquifer storage and recovery (ASR) defined reasons to do AR or ASR ASR concepts and issues

3 definitions AR = use of systems to increase the amount of water recharging an unconfined or confined aquifer ASR = recharge and temporary storage of (seasonally) available water in an aquifer with the intent to recover the water from the aquifer in the future

4 recharge options Water Table Modified from: Brand, C., An ASR Primer, 2008, Southwest Hydrology, Vol. 7, No. 3

5 where is ASR used? ASR used around the world as of 2009 there were over 500 ASR wells in the U.S.

6 why implement AR or ASR? water supply for routine, emergency, or drought demand (ASR) stop decline in aquifer water levels (AR & ASR) reduce peak water treatment needs (ASR) storage of water in an aquifer may be cheaper or more efficient than surface storage options (ASR) ecosystem restoration (AR) hydraulic barriers (AR)

7 implementing ASR recharge water source? seasonally available water (e.g., excess spring stream flow) drinking water aquifer (e.g., excess water pumped during low demand periods) WWTP effluent temporary storage where? drinking water aquifer brackish water or brine aquifer

8 implementing ASR (cont.) recharge method & treatment needs water table aquifer recharge: infiltration basins, in- or off-channel systems, injection wells Confined aquifer recharge: injection well recharge water treatment depends on water source & storage aquifer characteristics recovery method recharge well (dual purpose well) dedicated recovery well

9 implementing ASR (cont.) Proper design requires understanding hydraulic properties of the target aquifer lab testing of cores field infiltration/injection and pumping tests groundwater modeling for layout of system components permits in MN injection wells regulated by U.S. EPA

10 potential issues introduction of contaminants or pathogens into target aquifer treatment technology will depend on the contaminants/pathogens to be removed DBPs (e.g., trihalomethanes) could form as a result of disinfection

11 potential issues (cont.) mobilization of unwanted constituents (e.g., arsenic, iron, manganese, or radionuclides) sampling & testing of aquifer material, aquifer water, and recharge water to determine if unwanted constituents could be mobilized evaluate treatment alternatives to prevent mobilization

12 operation operational testing for injection wells injection and recovery cycles number depends on site/system specifics but typically will be 3 or more monitoring points in the aquifer

13 operation (cont.) pretreatment of recharge water is important to minimize plugging of injection wells ongoing system maintenance requirements vary depending on system details well redevelopment/rehabilitation basin flooding/drying cycles & unclogging

14 summary Growing water demands & potential decreases in natural recharge will require active aquifer management in the future. AR and ASR are ways to store excess water in times of plenty so it can be used in times of drought or peak demand or to address increasing annual demands on our aquifers. You ll hear about an ASR system that has been implemented in Minnesota in an upcoming talk. Thank You.