Water-rock interactions during ASR and effects on water quality

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Water-rock interactions during ASR and effects on
water quality
Aquifer Storage and Recovery IV AGWT/HC/FGS April
15-16, 2004 Tampa, Florida
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Acknowledgements

• Drs. Jim Cowart (FSU) and Adel Dabous (FGS)
• US Environmental Protection Agency
• FDEP/DWRM Bureau of Water Facilities Regulation -
  Underground Injection Control Program
• City of Tampa Water Department and CH2M Hill
• City of Punta Gorda/Montgomery Watson
• FSU Isotope Geochemistry Laboratory
• FDEP Bureau of Laboratories

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ASR role in CERP

• Divert part of the 1 trillion gallons of water
  that flows to tide each year
• 330 ASR wells 1.6 billion gallons per day
• Regional benefits
• Lower East Coast supplement the Biscayne Aquifer
• Caloosahatchee water supply and Caloosahatchee
  estuary health
• Lake Okeechobee water supply and lake health
• Three Pilot Studies and the Regional Study
• Investigate regional technical and regulatory
  issues governing the feasibility of full-scale
  ASR implementation, as identified in CERP, and
  develop tools to assess the viability and
  increase the level of uncertainty of successful
  ASR implementation.
• http//www.evergladesplan.org/index.htm
• http//www.sfrestore.org/

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ASR Issue Team/CROGEE recommendations for further
study 1. Characterization of the quality of
prospective source waters, spatial and temporal
variability 2. Characterization of regional
hydrogeology of the Upper Floridan aquifer
system hydraulic properties and water quality 3.
Analysis of critical pressure for rock
fracturing 4. Analysis of site and regional
changes in head and patterns of flow 5. Analysis
of water quality changes during movement and
storage in the aquifer system 6. Potential
effects of ASR on mercury bioaccumulation for
ecosystem restoration projects 7. Relationship
among ASR storage interval properties, recovery
rates, and recharge volume
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Purpose of study

• Investigate geochemical changes in native and
  recharge/recovery waters to
• characterize chemical evolution of waters
  involved in ASR
• characterize water-rock interactions due to ASR
  activities
• Identify mobility and source of trace metals
• Characterize chemistry and mineralogy of aquifer
  matrix
• Evaluate affects of repeated ASR cycle testing on
  quality of recovered water
• Provide FDEP, CERP and other agencies with
  science-based information on which to base policy
  and planning decisions

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Study Areas Rome Ave. ASR, Hillsborough
Co. Punta Gorda ASR, Charlotte Co. Peace River
ASR, De Soto County
LANDSAT S. Fl peninsula
Comprehensive Everglades Restoration Plan
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Rome Avenue Park ASR Site Map
Transmission Pipeline Back to WTP
ASR-1
W
.

S
l
i
g
h

A
v
e
.
ASR-2
Proposed SZMW-5 Location
ASR-3
ASR-4
ASR-8
ASR-5
ASR-6
ASR-7
Rome Avenue Park Site 10 mgd Potable Water ASR
Courtesy CH2M Hill DRAFT
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Punta Gorda ASR
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Recovery begins
?
C
Injection concentration
Native concentration
T
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Proposed MCL 20ug/l
90-90-90 Mixing/dilution Re-precipitation Mobiliza
tion decreases
Mixing/dilution Var. mobilization Alt. pathways
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Rome Ave. ASR
ASR
MW
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Rome Ave. ASR 7, Phase II, 2001

• Shorter duration
• Same max value

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The Uranium Story...

• Three naturally occurring isotopes 238, 235, 234
• 238-U decay series contains 15 radioactive
  isotopes of eight elements
• 238-U 234-Th 234-Pa 234-U ...206-Pb
• (? decay -2n, -2p) (? decay -1e) (?
  decay -1e)
• Alpha activity ratio (daughter/parent)
  234U/238U
• Secular equilibrium AR 1
• Disequilibrium AR?1
• Applications groundwater evolution, mixing,
  sources

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Native and input water
ALPHA ACTIVITY RATIO
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Punta Gorda ASR
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Cycle Test Summary
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Arsenic (As) in ground water

• Recent EPA MCL 50 ug/l WHO 10 ug/l
• New MCL 10 ug/l (January, 2006)
• 10 of 30,000 As analyses of gw exceed 10 ug/l in
  US
• 30 of 50 million people are feared to be at
  risk from As exposure in India and Bangladesh.
• Anthropogenic sources
• agriculture
• insecticides
• phosphate fertilizers can mobilize As into ground
  water
• wood preservation
• glass production
• 30 of 1191 Superfund sites list As as a
  contaminant of concern
• atmospheric deposition

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Arsenic (As) in ground water

• As in the hydrogeologic environment as
• Arsenate (As 5), arsenic acid
• Arsenite (As 3), arsenite hydroxide
• Mechanisms for mobilization and increased ground
  water concentration
• Oxidation of sulfide minerals (up to 60,000 ppm)
• Fe and Mn hydroxides (30 - 500 ppm As in grain
  coatings)
• Oxidation - reduction of organic material
• Biological transformations (bacteria can increase
  oxidation rates)
• Evaporative concentration in shallow ground water
• Geothermal water

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Matrix analytical work
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Aquifer matrix geochemistry

• Major elements
• Trace elements
• Rare earth elements
• Relation between metals and organics
• Gamma-ray activity and organics/metals

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Selected metals concentrations (n36) Limest
one Element min max avg. global avg. Fe2O3
(wt.) .04 .39 .15 .11 MgO (wt.) 0.6
19 1.74 2-20 MnO (wt.) bd .02 .02
.01 K2O (wt.) .02 0.2 .04 .04 As
(ppm) bd 54 3 2.5 Cr (ppm) bd
53 17 10 Hg (ppb) bd 158 42 30 S (wt. )
bd 1.7 .08 .06 Ni (ppm) bd 19 4 12 U
(ppm) bd 28 5 2 bd - below detection -
Price and Pichler, 2004 (in review)
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• Trace Mineralogy and the search for As
• Petrography
• X-ray diffraction
• SEM/EDX microprobe

SEM/EDX probe
XRD
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ASR 3-2Tj 5mm
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Pyrite Calcite
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Courtesy USF Geology
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• Pyrite mode of occurrence
• intergranular (along pore spaces)
• intragranular
• clay-associated
• framboidal masses
• low-As (lt2wt)
• up to 10 microns (see scale bar)
• Other observations
• gypsum
• quartz (euhedral)
• organics (C, N, O) gt
• (Ca, S, Si, Ti) As

Price and Pichler, 2004, in review
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Sequential Extraction
I
Phase
II
III
IV
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Current and planned activities

• Effects of pH-adjusted cycle tests and borehole
  acidization
• Effects of multiple cycle tests on water quality
• Continued aquifer matrix geochemical
  characterization for other SZ lithostratigraphic
  units (Hawthorn Group, Ocala Ls., Avon Park Fm.)
• Mineral/phase chemistry
• Sequential extraction and bench scale leaching
  experiments
• Arsenic speciation
• Monitor behavior of other metals in ground water
• Include more hydrogeologic settings

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Data and Research needs

• Cores from ASR storage zones
• WQ during recharge, storage and recovery from ASR
  and MWs
• Predictive tools
• Bench-scale leaching studies
• Geochemical modeling

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Conclusions

• The Floridan aquifer system matrix is not
  chemically homogenous.
• Mobilization of As, Fe, Mn, and U others (Ni, V,
  Mo?)
• WQ, redox conditions, mineralogy and rock
  chemistry are consistent with arsenian pyrite
  oxidation and dissolution/leaching
• Mobility variables include
• water chemistry (native and input) ? DO, pH
• aquifer matrix chemistry/mineralogy
• input water volume, matrix contact time, number
  of cycle tests
• site-specific hydrogeology/geochemistry
• Uranium isotopes are useful toward understanding
  groundwater evolution during ASR activities.
• Inadequate monitoring frequency
• may yield misleading results

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Questions?
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