Aquifer Storage and Recovery Challenges and Solutions Frederick Bloetscher, Ph.D., P.E. Florida Atlantic University

Why Pursue ASR? Store water for Future Raw water Potable water Irrigation Fire/other Blend water for quality purposes Water quality improvements

DEPTH (Feet Below Land Surface) ASR Concept TREATMENT PLANT ASR WELL DURING INJECTION ASR WELL DURING RECOVERY LAND SURFACE 0 WATER TABLE AQUIFER CONFINING BED 100 200 CONFINING BEDS 300 400 500 CONFINED SYSTEM 600 MIXING ZONE INJECTED POTABLE WATER

What the wellhead looks like

Number of ASR Well Sites Where is ASR being implemented? 60 50 40 30 20 10 0 FL CA NJ AZ OR SC WA CO TX NV IA UT DE GA ID KS NC NY VA WI WY IL MN NM OK SD TN State

100 Well Sites by decade 75 50 25 0 1960s 1970s 1980s 1990s 2000s post 2010

So you want to know more.. Water Source Well construction Aquifer formation Operations Equipment Issues that can arise

Typical sources of water Surface Water, 129, 64% Other, 1, 1% Reclaimed, 28, 14% Ground Water, 43, 21%

Reported uses of recovered water Canal Recharge, 2, 1% Potable Supply, 108, 53% Raw, 52, 26% Fire, 2, 1% Cooling Water, 3, 1% Irrigation, 37, 18%

Typical types of casing material Steel, 120, 77% Fiberglass, 3, 2% PVC, 32, 20% Stainless Steel, 2, 1%

Well Construction

Column Pipe Inner casing Outer casing Surficial Formation Confinement Intermediate Casing Confinement Submersible Pump Screen Injection Horizon

Relative frequency Casing Diameter 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 0 10 20 30 40 50 60 Casing Diam.

Relative frequency Relative frequency Typical well depths 0.3 0.25 0.25 0.2 0.2 0.15 0.15 0.1 0.1 0.05 0.05 0 0 500 1000 1500 2000 2500 3000 Depth of casing 0 0 1000 2000 3000 4000 5000 Depth of well

Formation - storage zone lithology Basalt Carbonate 8% 1% Alluvial 33% Limestone 33% Sandstone 11% Granite 0% Sand / Clay 6% Sandstone 8%

Lithology of confinement Clay 34% Limestone 14% Granite 3% Silt / Basalt 8% Shale 6% None 3% Alluvial 1% Basalt / Clay 16% Dolomite 15%

Relative frequency Relative frequency Injection Horizon Thickness 0.3 0.7 0.6 0.25 0.5 0.2 0.4 0.3 0.15 0.2 0.1 0.1 0.05 0 0 1000 2000 3000 4000 5000 Injection Horizon 0 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Injection Horizon

Relative frequency TDS 0.25 0.2 0.15 0.1 0.05 0 0 5000 10000 15000 20000 25000 30000 35000 40000 TDS

Relative Frequency Transmissivity 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 0 100000 200000 300000 400000 500000 600000 700000 Transmissivity (gpd/sf)

Relative frequency Operations- Injection rate of wells (MGD) 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 0 5 10 15 20 injection Capacity (MGD)

Relative frequency Rate of Recovery of Injected Water (MGD) 0.3 0.25 0.2 0.15 0.1 0.05 0 0 5 10 15 20 Withdrawal Capacity (MGD)

Relative frequency Ratio (In:out) 0.6 0.5 0.4 0.3 0.2 0.1 0 0 1 2 3 4 5 6 Ratio Injection to Withdrawal

Data Collection Number of cycles per site 5 to 10 11% 2 to 5 43% 10 to 20 26% 0 to 1 9% > 20 11%

Relative frequency Water stored (millions of gallons) 0.8 Histogram (Amount of Water Stored (MG)) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 10000 20000 30000 40000 50000 60000 70000 80000 Amount of Water Stored (MG)

Relative frequency ASR recovery rates for the ASR sites (MGD) 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Source: Reese, USGS 0 20 40 60 80 100 Peak Flow on Site (MGD)

Records Drawdown Pump Rate Power Use Specific Capacity Water Quality (temperature, conductivity, ORP, silt density index, ph, ions before and after injection, metals)

Growth By Decade

Location of ASR Wells with Time

Source Water with Time

Water Use with Time

Injection Formation with Time

Status with Time

Challenges Encountered

Challenges 1. Prohibition (GA reintroduced in 2015) 2. Thm regulation issues (potable and reuse water have chlorine) 3. Water rights after injection who s water? 4. Storage time (how long - 6 mo? 1 mo? 3 yrs?) 5. Recovery what % is acceptable (20? 40? 70?) 6. Metals mobilization (FL, WI, others) 7. Clogging (just like any well, but injection accelerates it) 8. Expectations of clients (cheap, fast, high recovery, no treatment)

Georgia In 1996, TSG (The Savannah Group Water Services) a water supply company, applied for three surface water withdrawal permits Georgia Legislature enacted a moratorium on ASR in 1999 for 11 coastal counties, effectively ending the TSG proposal. The moratorium expired in 2014 Georgia Regional Commission (SWGRC) submitted a Governor s Water Supply Program (GWSP) application for a $13.5 million experimental large flow augmentation program for the Flint River project

Georgia Starting in the fall of 2014, discussion about extending the ban on ASR developed. Senate bill 36 was introduced to require the Board of Natural Resources to adopt regulations that provide for the protection and preservation of the Floridan aquifer No companion in the Senate House Study Committee on Saltwater Intrusion into Coastal Aquifers, but the directive does not include the SB 36 language. More to come

Florida Water must meet Florida s drinking water standards prior to injection into an ASR well Water quality changes include arsenic and other metals mobilization. Arsenic mobilization in limestone was reported in Florida wells The arsenic issue in Florida did not affect many sites until 2005, when the federal drinking water standard for arsenic was reduced from 50 ug/l to 10 ug/l.

Florida The Florida ASR wells with levels of arsenic above the 2005 standard all use the same Floridan limestone formation. Oxygenated water can release naturally-occurring arsenic from underground limestone formations and raise arsenic levels In 2012, the Florida Department of Environmental Protection (DEP) sought a regulatory approach that would allow the use of ASR while addressing the drinking water standards.

Solution Zone-of-discharge Preventing the endangerment of adjacent underground drinking water sources through monitoring Preventing public access to that portion of the aquifer by ensuring that the operator of the facility owns or otherwise controls the installation of wells within the property overlying the zone of discharge FDEP may reach the necessary non-endangerment finding

Zone of Discharge Defined in the regulation as a volume underlying or surrounding the site and extending to the base of a specifically designated aquifer or aquifers, within which an opportunity for the treatment, mixture or dispersion of wastes into receiving ground water is afforded.

Results EPA agreed DEP issued permits for Tampa Rome, Destin Reuse, Bradenton, Punta Gorda, Naples, Lee County Corkscrew, Peace River and Sarasota County Central WRF ASR wells Orange County, Collier Livingston Road, West Palm Beach, Sanford all active

Challenge Solutions Wells will likely need to be treated to deal with clogging Treatment may be required for metals, ORP Wells need extended testing and multiple cycles with large injection and storage times Recovery may be adjusted by adjusting withdrawal rates

CERP ASR

Source: ACOE Treatment may be Extensive

Recovery Time is Relevant Injection zone water quality matters

Recovery with Time?

In Short, Expectations Not always fast Not always cheap Not always high recovery May need treatment May need more wells than you think But these are issue to deal with as the project evolves!

Summary ASR an be a useful tool to help manage water supplies, but manage expectations The type of formation, its transmissivity, and confinement are the major issues for quick, less cost projects Clogging is an ongoing issue with all water, but esp raw surface water and reclaimed water Success is not a short term issue

Questions?