Robert Macias, San Antonio Water System James Dwyer, P.E., CH2M HILL
Agenda Edwards Aquifer A sole-source aquifer for the San Antonio Water System (SAWS) EAA permit and implications for SAWS Aquifer storage and recovery as a drought management strategy System details Historical performance Future Operation Under EARIP Summary
San Antonio, Texas
The Edwards Aquifer; A Unique Ecological System
The Edwards Aquifer; A Unique Ecological System Dr. Glenn Longley
The Edwards Aquifer; A Unique Ecological System Dr. Glenn Longley Dr. Glenn Longley
The Edwards Aquifer; A Unique Ecological System Dr. Glenn Longley Dr. Glenn Longley Dr. Glenn Longley
The Edwards Aquifer; A Unique Ecological System Dr. Glenn Longley Dr. Glenn Longley Dr. Glenn Longley Gregg Eckhardt
Sole-source aquifer Springs historically dependable source 1719 - First recorded use by Spanish missions 1891 First municipal supply well 1959 - Edwards Underground Water District created primarily to study and monitor, no regulatory authority 1975 - EPA designated Edwards as the first "sole source aquifer"; more than 50% of supply, no readily available alternative
Edwards Aquifer Authority Permit Critical period triggers based on 10-day average J17 level and/or flow in Comal or San Marcos Springs Stage I 20% cut Stage II- 30% cut Stage III 35% cut Stage IV- 40% cut
Historical Perspective 660 MSL 630 MSL
Historical Perspective Daily High (Elev) 690 680 670 660 650 640 J17 630 620 610 J-89 M-89 M-89 J-89 S-89 N-89 J-90 M-90 M-90 J-90 S-90 N-90 J-91 M-91 M-91 J-91 S-91 N-91 J-92 677 days @ 20% Reduction
Historical Perspective Daily High (Elev) 690 680 670 660 650 640 J17 630 620 610 J-89 M-89 M-89 J-89 S-89 N-89 J-90 M-90 M-90 J-90 S-90 N-90 J-91 M-91 M-91 J-91 S-91 N-91 J-92 677 days @ 20% Reduction 162 days @ 35 % Reduction
What is ASR? Environmentally friendly method of storing drinking water Edwards Aquifer water is transported from SAWS distribution system and stored in the Carrizo Aquifer Water stored during wet or low use periods (winter), recovered during times of drought ASR used to help maximize future allocations of Edwards Aquifer water
Edwards Optimization Monthly Demand ASR Storage ASR Recovery Annual Average Demand ASR Storage J F M A M J J A S O N Months D
ASR Injection Mode How ASR Works
ASR Recovery Mode How ASR Works
SAWS ASR Program Overview 30 Million Gallons per Day (MGD) Treatment Capacity 70 MGD High Service Pumping Capacity 60 MGD ASR Wellfield Storage Capacity 64 MGD Pipeline Capacity Integrates into the SAWS System at Artesia, Seale, and Randolph Pump Stations
Operations 120,000 ASR Storage History (4-15-14) Cumulative Storage (ac-ft) 100,000 80,000 60,000 40,000 20,000 0 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Merging EARIP and SAWS ASR EARIP deliberations realized that the SAWS ASR may be useful as one component in a group of program components referred to as Bottom Up activities SAWS ASR holds the potential to address endangered species requirements and prevent the need for a new water resource project Merging the EARIP and SAWS use of the ASR reduces the total cost overall EARIP plan
ASR with EARIP SAWS manages the ASR whenever the J-17 well exceeds 630 feet msl SAWS may need to recharge between 630 and 660 feet msl When the J-17 well drops below 630 feet msl, and the region is in the Drought of Record (DOR), the ASR becomes dedicated to EARIP s habitat protection plan Production mode only Modeling shows that ASR will need to provide approximately 126,000 acre-feet of water, over eight years to meet a future DOR
EARIP & SAWS ASR Simulated operations contribute to a ~30 cfs benefit
Protecting Comal Spring Flows 160 140 120 100 Simulated 593,000 AF pumping + no management strategies in place = 39 months of zero spring flow cfs 80 60 40 20 0 Jan-52 Jan-53 Jan-54 Jan-55 Jan-56 Jan-57 Baseline
Phase I Components and ASR cfs 160 140 120 100 80 60 40 20 0 Jan-52 Jan-53 Jan-54 Jan-55 Jan-56 Jan-57 Baseline Other Strategies ASR Phase I
SAWS ASR Flexible operations have been displayed with the early implementation of ASR technology by SAWS Project has exceeded all expectations Stored water quality looks as expected Valuable storage for San Antonio EARIP strategy
Moving forward with ASR Regional EARIP commitment Maintain bank in long-term storage SAWS Water Management Plan (WMP) Explore effective summer peak management strategies Plan for future studies to more effectively understand hydrogeology of site Phase II EARIP Possibly further protect springflow, if necessary