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 ( 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: