Transcript Alternative Water Resource of Duval County

Alternative Water Resource
of Duval County
Hawthorn Formation
Intermediate Aquifer System (IAS)
The Neglected Aquifer
By:
Vijay Satoskar, Ph.D., P.G.
City of Jacksonville, EQD
Acknowledgements
• Dr. Jonathan Arthur (Director, FGS) and Dr. Tom Scott
(former Dy. Director, FGS) for their enthusiastic support
re: Hawthorn to be looked as an “aquifer” instead of a
“confining layer” for Northeast Florida.
• SJRWMD for the utilization of the web-based ViewLog
software, especially Jeff Davis and Dr. Ima Bujak.
• The Environmental Quality Division (EQD) of COJ for the
Hawthorn Project support, especially Gary Weise for his
strong encouragement.
Potential Priority Water Resources Caution Areas
(PPWRCAs)
Duval
Advantages of the Hawthorn (IAS)
•
Supplemental potable water resource, as an alternative to the Floridan
(FAS) Aquifer, extending the sustainability of FAS.
•
Additional withdrawals from FAS potentially may result in increased
salt water intrusion due to fracture-related up-welling.
•
Ideal secondary water resource for geothermal, irrigation, industrial,
etc. uses.
•
Lower TDS (total dissolved solids) than FAS.
•
Less expensive potable water resource: Lower drilling cost (shallower
depths), less well permit costs (O.C.123), etc.
•
Easier and within-County recharge potential with strategic location of
recharge ponds-associated parks. A better manageable renewable
resource with greater aesthetics possibilities!
Why has the Hawthorn Fm. (IAS) Of Duval Co.
been neglected so far?
• IAS is too complex and variable in availability: requires
analytical well completion/development skills to optimize
yields.
• FAS is almost uniform and homogeneous: “ just punch a
hole into it and get all the water”. The Ocala Limestone
(Upper FAS) is a widespread aquifer and highly
productive. A “guaranteed” water well.
The rest of the U.S. would be thrilled to have
the IAS of NE Florida!
Hawthorn Formation
The Hawthorn formation is of the Miocene
age and directly overlies the Eocene age
Ocala limestone (the Upper Floridan
Aquifer) which is the primary potable water
resource of northeast Florida. Hawthorn
formation consists of primarily terrestrial,
alluvial and deltaic sandy and clayey
sediments with a minor amount of marine
carbonates at the base of the formation.
What makes Northeast Florida so favorable for
Hawthorn (IAS)?
•
Favorable Geology: Plate Tectonics/ Continental Drift
creating favorable subsurface structural framework
•
Passive Continental Margins: Tensional faults, rifts (grabens), etc.
•
The Jacksonville Graben - thicker sedimentary basin (similar to the Blake
Plateau of offshore Jacksonville)
•
During the Miocene/Pliocene times (5-25 m. yrs ago), the Jacksonville
Graben was filled by alluvial and marine deposits, such as deltas and sands
bars & dunes, resulting in a number of permeable sand beds called the Salt
& Pepper Sandstone (S&P) beds. At the deepest portions of the Graben,
the Hawthorn (IAS) may contain more than 10 different permeable S&P
beds of varying thicknesses.
Tectonic History of N. America (Florida)
• Westward movement of the N. American plate has
created tensional fractures (rift valleys or “grabens”)
along the passive continental margin.
• A major graben (200-100 m. yrs old) is represented
by the Blake Plateau, offshore Jacksonville.
• A minor graben (generally referred to as the
“Jacksonville Basin” and approx. 25 m. yrs old)
occurs in Duval County, as a part of the Southeast
Georgia Embayment.
Passive
N. American
Margin
Offshore
Continental
Margin
Blake Plateau, Offshore Florida “Graben”
NE Florida’s Groundwater Resources:
Floridan (FAS), Intermediate (IAS) & Surficial (SAS) Aquifer Systems
Wells with Geophysical and Lithologic Logs
from Duval County and surroundings
X-section along South Boundary, Duval Co.
Central Duval Co. X-Section
Northern Cross-Section
Duval County X-sections (E-W & N-S)
Duval County West to East Section
Duval County South to North Section
Duval Co.’s Jacksonville Basin (a graben)
Hawthorn (IAS) Feasibility
Hydrogeologic setting confirms a potential
for the Hawthorn to be a productive
supplementary aquifer in NE Florida
• Structural framework
• Thickness of the sedimentary deposits
• Higher transmissivity within the graben
Future Studies of Hawthorn (IAS)
• Define hydraulic characteristics
• Determine thickness and extent and water
chemistry of the permeable S&P sands
• Determine locations of fractures and limits
of the graben
Planned Comprehensive Projects
Hawthorn (IAS) Study
• U.S.Geological Survey will be collaborating with EQD
to determine the groundwater availability of Hawthorn
(IAS) of Duval County and surroundings.
• More funding and stakeholders are needed to
conduct the comprehensive IAS Feasibility Study of
Duval County (and surroundings).
Planned Comprehensive Projects
Tree Hill Nature Center (THNC) Geothermal
Project
The EPB/DOE-funded geothermal energy system at
THNC will be based on Hawthorn supply and injection
wells and will serve as a demonstration for:
1) groundwater as an efficient alternative energy
resource and,
2) efficacy of IAS as a secondary water resource.
Contact Information
• Dr. Vijay Satoskar, P.G.
City of Jacksonville, EQD
Tel: 904-255-7121
e-mail: [email protected]