Prepared in cooperation with Broward County Environmental Planning and Community Resilience Division Integration of Seismic-Reflection and Well Data to Assess the Potential Impact of Stratigraphic and Structural Features on Sustainable Water Supply from the Floridan Aquifer System, Broward County, Florida

Overview Seismic- Hydrogeologic unit Geologic unit stratigraphic unit The U.S. Geological Survey (USGS) and Broward Holocene sediments Biscayne aquifer not defined County water managers commenced a 3.5-year cooperative Pleistocene formations study in July 2012 to refine the geologic and hydrogeologic SSB

Surficial Confining beds

framework of the Floridan aquifer system (FAS, fig. 1) in aquifer system Gray limestone Tamiami Formation aquifer Stock Broward County (Cunningham, 2013). A lack of advanced Island SSB 1 Formation 2 stratigraphic knowledge of the physical system and structural SSB geologic anomalies (faults and fractures originating from Peace River 3 SSB tectonics and karst-collapse structures) within the FAS pose a Formation risk to the sustainable management of the resource. Confining unit 4 SSB The principal objective of the study is to better define 5

Hawthron Group SSB the regional stratigraphic and structural setting of the FAS Arcadia Formation Intermediate confining unit SSB 6 in Broward County (fig. 1). The objective will be achieved 7 SSB 8 through the acquisition, processing, and interpretation of new SSB 9 seismic-reflection data along several canals in Broward Upper Floridan SSB aquifer County. The interpretation includes integration of the new 10 seismic-reflection data with existing seismic-reflection Middle semiconfining profiles along Hillsboro Canal in Broward County unit 1 Avon Park Formation SSB (Cunningham, 2013; Reese and Cunningham, 2014) and APPZ within northeast Miami-Dade County (fig. 2), as well as with 11 Middle semiconfining data from nearby FAS wellbores. The scope of the study unit 2 SSB includes mapping the geologic, hydrogeologic, and seismic- Floridan aquifer system LF1 Lower 12 reflection framework of the FAS, and identifying stratigraphic Floridan 13 aquifer and structural characteristics that could either facilitate or BZ Oldsmar Formation 14 preclude the sustainable use of the FAS as an alternate (Includes permeable zones and confining units) water supply or a treated effluent repository. In addition, the Cedar Keys Formation 15 investigation offers an opportunity to: (1) improve existing Sub-Floridan confining unit

groundwater flow models, (2) enhance the understanding (Includes permeable zones Upper Cretaceous 16 and confining units)

of the sensitivity of the groundwater system to well-field Sub-Floridan units Lower Cretaceous 17–18 development and upconing of saline fluids, and (3) support EXPLANATION site selection for future FAS projects, such as Class I wells APPZ Avon Park permeable zone Geologic unit boundary– LF1 Uppermost major permeable dashed where that would inject treated effluent into the deep Boulder poorly defined Zone (fig. 1). zone of the Lower Floridan aquifer Seismic-stratigraphic unit boundary–dashed BZ Boulder Zone where poorly defined SSB Seismic-sequence boundary

Data Acquisition and Processing Figure 1. Generalized hydrogeologic units of eastern Broward County and correlation to seismic-stratigraphic units identified Approximately 60 miles of high-frequency, marine in seismic reflections and to geologic units. Modified from Reese seismic-reflection data were acquired by Walker Marine and Cunningham (2014) and uses information from Roberts-Ashby Geophysical Company in canals in eastern Broward County and others (2013). during 2013 (fig. 2). Excel Geophysical Services performed

U.S. Department of the Interior Open-File Report 2014–1136 U.S. Geological Survey August 2014 80°20’ 80°10’

PB-1766

PALM BEACH COUNTY Hillsboro Canal G-2984 26°20’ BROWARD COUNTY

G-2968 SAWGRASS EXPRESSWAY 95

441 Study area EXPLANATION Probable karst collapse structure Coral Springs

Canal L-36 Canal L-36 Road Line of seismic-reflection data acquired previously C-14 Canal Line of seismic-reflection data acquired for this study IW-3 Well with synthetic seismogram G-2984 USGS test corehole

FLORIDA’S TURNPIKE 0 2.5 5 MILES G-2938 0 2.5 5 KILOMETERS

26°10’ Line NNRW26APR C-13 Canal PLT-I1 Figure 3 C-12 Canal L-35A CanalSunrise Fort IW-3 Lauderdale Arbitrary Line NNRW2 + NNRE North New River Canal G-2981 G-2971 City of Sunrise FTL-I5 Injection Well Line NNRCOM3D System 595

75 ATLANTIC OCEAN C-11 Canal

1 C-10 Canal G-2961

G-2973 Pembroke Pines Hollywood 26°00’ PBP-IW-1 G-2973

BROWARD COUNTY G-2945 MIAMI-DADE COUNTY C-9 Canal

IW-2 Hialeah C-8 Canal IW-3 DZMW-1

Figure 2. Locations of newly acquired (red lines) and existing (orange lines) seismic-reflection surveys used in the ongoing cooperative study between the U.S. Geological Survey and Broward County. Also shown are locations of probable karst-collapse structures interpretated on seismic-reflection profiles and locations of seismic-reflection profiles presented in figure 3. post-acquisition processing of the seismic-reflection data Structural features—Cunningham and Walker (2009), to produce 36 new seismic-reflection profiles (for example, Cunningham and others (2012), Cunningham (2013), and fig. 3). Additional processing occurred at the Department of Reese and Cunningham (2014) describe evidence of tectonic Earth and Planetary Sciences, University of California-Santa faults and karst-collapse structures on seismic-reflection Cruz, as part of a USGS Cooperative Ecosystem Studies profiles acquired in southeastern Florida. These faults and Unit agreement. Most of the seismic-reflection profiles karst-collapse structures can span from the intermediate con- are interpretable to a two-way travel time depth of about fining unit, the semiconfining and confining units included in 0.75 second. Notably, one profile (NNRCOM3D, figs. 2 and 3) the FAS, and sub-Floridan units (figs. 1 and 3). has an interpretable record to a two-way travel time depth Although preliminary observations have not identified of about 1.5 seconds. Eleven seismic-reflection profiles any tectonic faults on the new seismic-reflection data generated in one previous Broward County study (Reese acquired from Broward County, they have indicated and Cunningham, 2014) and one ongoing USGS study in numerous probable karst-collapse structures on nine seismic- Miami-Dade County augment the inventory of available reflection profiles (figs. 2 and 3; Cunningham, 2013, fig. 3). seismic-reflection profiles. Specialized geophysical software Seismic-reflection line NNRCOM3D (figs. 2 and 3) was used to generate 15 synthetic seismograms using velocity displays one of the karst-collapse structures. This structure data from borehole-compensated sonic logs as input (fig. 2). extends upward possibly from Lower Cretaceous carbonate The process of calibration of geologic properties in boreholes rocks (Unit 17) to the approximate top of the Peace River to seismic-reflection profiles uses synthetic seismograms. Formation (locally Unit 3, fig. A3 ), which is approximately See Cunningham (2013, fig. 6) for an example of a synthetic coincident with the top of the intermediate confining unit seismogram produced using sonic-log data from a well in throughout part of the study area (fig. 1). The location of Broward County. the karst-collapse structure on seismic-reflection profile NNRCOM3D is along the North New River Canal about 3,000 feet to the south of the City of Sunrise Injection Data Interpretation Well System (fig. 2). Detection of treated effluent in the uppermost major permeable zone of the Lower Floridan The principal focus of the study is to interpret the aquifer at this injection well system indicates that the source seismic-reflection data, including its integration with well is upward migration of treated effluent from the Boulder Zone data. Maps of geologic units and hydrogeologic units will (fig. 3B; Montgomery Watson, 1996). Montgomery Watson be constructed by integrating the two-dimensional seismic- (1996) indicates that the migration of treated effluent from reflection data and one-dimensional well data using seismic- the Boulder Zone to the uppermost permeable zone of the reflection interpretation software. Maps will be produced that Lower Floridan aquifer (fig. B3 ) was a result of the lack of show the depths of key horizons in two-way travel time as confinement between the two permeable zones and “not of well as in feet. lack of mechanical integrity in the existing injection wells.” Within the City of Sunrise Injection Well System, the absence Seismic-sequence stratigraphy—Preliminary stratigraphic of confinement between the uppermost major permeable analysis of the seismic-reflection data identified 18 provisional zone of the Lower Floridan aquifer and the Boulder Zone is seismic-stratigraphic units, which probably extend from the possibly enhanced by faults, fractures, and karst dissolution uppermost rocks of the Lower Cretaceous and to the base of associated with the karst-collapse structure imaged on profile Pleistocene rocks and sediments (figs. 1 and 3). Many of the NNRCOM3D (figs. 2 and 3). A more dense occurrence of provisional seismic-stratigraphic units are seismic sequences diffractions and offsets in seismic reflections exists in the sensu stricto (Mitchum and others, 1977), which provide Boulder Zone and the overlying part of the Lower Floridan information for developing a seismic-sequence framework in aquifer upward to the top of the uppermost major permeable southeastern Florida. Fortunately, the Upper Floridan aquifer, zone of the Lower Floridan aquifer (fig. B3 ). Seismic- Avon Park permeable zone, the uppermost major permeable reflection data therefore provide useful evidence for the zone of the Lower Floridan aquifer, and the Boulder Zone presence of faults and fractures that can plausibly function as have predictable vertical positions that are included in the permeable pathways, where fluids can migrate upward. seismic-stratigraphic units 8 to 15, and therefore seismic- reflection stratigraphy provides a means for the detailed mapping of these hydrogeologic units (figs. 1 and 3). The use of seismic stratigraphy allows, for the first time in southeast- References Cited ern Florida, a level of resolution in mapping of hydrogeo- logic units never before accomplished using well data alone. Applin, P.L., and Applin, E.R., 1965, The Comanche Series Notably, the seismic stratigraphy can inform groundwater and associated rocks in the subsurface in central and south simulations designed to address the sustainability of the water Florida: U.S. Geological Survey Professional Paper 447, resources of the FAS. 84 p. (http://pubs.er.usgs.gov/publication/pp447) A

Depth below canal level, in feet USDW Base 8,500 8,000 7,500 7,000 6,500 6,000 5,500 5,000 4,500 4,000 3,500 3,000 2,500 2,000 1,500 1,000 500 0

Two-way travel time, in seconds WEST 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 UF BZ LF1 APPZ Surficial aquifer APPZ UFA TPH LF1 A Fm BZ 5 Formation Boulder Zone LowerFloridanaquifer Uppermost majorpermeablezoneofthe zone Avon Parkpermeable Upper Floridanaquifer Holoceneformations Tamiami Formation,andPleistocene Inset B Possible faultorfracture Seismic-stratigraphic unit(fig.1) whereuncertain Seismic-stratigraphic boundary–dashed Permeable zone EXPLANATION NNRW2 SAS LK water(USDW) sourceofdrinking Base ofunderground 1.8 Miles Surficial aquifersystem Lower Cretaceous system paleocave collapsed Possible NNRE NNRCOM3D 13 11 15 12 10 18 16 17 14 1 8 9 3 5 6 7 EAST LK ? Upper Cretaceous Cedar Keys Formation Oldsmar Formation Avon Park Formation Arcadia Formation Peace River Fm TPH Sub-Floridan units Floridan aquifer system Intermediate confining unit SAS seismic-reflection profilesNNRW2,NNRE,and NNRCOM3D. (BZ). Seismic-stratigraphic units2and4(fig.1) arenotpresentin migrated alongfaultsandfractures upwardfromtheBoulderZone Lower Floridanaquifer(Montgomery Watson, 1996)thatplausibly been detectedintheuppermost majorpermeablezone(LF1)ofthe compared tounit11.Upwardmigration oftreatedeffluenthas of faultsandfracturesinseismic-stratigraphic units15-12,as others (2013,fig.8).( 9) andtopoftheUpperCretaceousbasedonRoberts-Ashby Top ofLowerCretaceous basedonApplinand(1965,Plate Cretaceous totheapproximatetopofPeaceRiverFormation. karst-collapse structurethatextendsupwardfromtheLower reflections onprofileNNRCOM3Dprovideevidencefora NNRCOM3D (locationsshowninfig.2).( Figure 3. about 3,000feetontoseismic-reflectionprofileNNRCOM3D City ofSunriseInjectionWell Systemprojectedsouthward Lower density of faults and Greater density of faults and fractures than unit 11 fractures than units 15–12

B Seismic-reflection profiles NNRW2, NNRE, and Seismic-reflection profilesNNRW2,NNRE,and USDW Base LF1 B ) Inset from fig. 3A showing greater density ) Insetfromfig.3Ashowinggreaterdensity Sunrise InjectionWell System Effluent detectedatCityof BZ 13 A ) Sagging seismic ) Saggingseismic 11 15 14 12 Cunningham, K.J., 2013, Integrating seismic-reflection and Mitchum, R.M., Jr., Vail, P.R., and Thompson, S., III, 1977, sequence-stratigraphic methods to characterize the hydro- Seismic stratigraphy and global changes of sea level, Part 6–– geology of the Floridan aquifer system in southeast Florida: Stratigraphic interpretation of seismic reflection patterns in depositional sequences, in Payton, C.E., ed., Seismic stratig- U.S. Geological Survey Open-File Report 2013–1181, 8 p. raphy—Applications to hydrocarbon exploration: American (http://pubs.usgs.gov/of/2013/1181) Association of Petroleum Geologists Memoir 26, p. 117–133. Cunningham, K.J., and Walker, C., 2009, Seismic-sag structures in Tertiary carbonate rocks beneath southeastern Montgomery Watson, 1996, City of Sunrise, Florida––Sunrise Florida, USA––Evidence for hypogenic speleogenesis?, injection well system reaffirmation of the external mechani- in Klimchouk, A.B., and Ford, D.C., eds., Hypogene cal integrity of IW–1 and IW–2: Lake Worth, Florida, speleogenesis and karst hydrogeology of artesian basins: Montgomery Watson, 55 p. Ukrainian Institute of Speleology and Karstology, Special Paper No. 1, Simferopol, Ukraine, p. 151–158. (http:// Reese, R.S., and Cunningham, K.J., 2014, Hydrogeologic institute.speleoukraine.net/libpdf/Cunningham%20Walker_ framework and salinity distribution of the Floridan aquifer SEISMIC-SAG%20STRUCTURAL%20SYSTEMS%20 system of Broward County, Florida: U.S. Geological Survey IN%20FLORIDA_HypoConf_2009.pdf) Scientific Investigations Report 2014–5029, 60 p. http://( dx.doi.org/10.3133/sir20145029) Cunningham, K.J., Walker, C., and Westcott, R.L., 2012, Near-surface, marine seismic-reflection data define potential Roberts-Ashby, T.L., Stewart, M.T., and Ashby, B.N., 2013, An hydrogeologic confinement bypass in the carbonate Floridan evaluation of porosity and potential use for carbon dioxide aquifer system, southeastern Florida: Society of Economic storage in the Upper Cretaceous Lawson Formation and Geophysicists Annual Meeting, Las Vegas, Nev., 6 p. Paleocene Cedar Keys Formation of south-central and south- (http://library.seg.org/doi/abs/10.1190/segam2012-0638.1) ern Florida: Environmental Geosciences, v. 20, p. 109–135.

By Kevin J. Cunningham U.S. Geological Survey Carbonate Aquifer Characterization Laboratory 7500 S.W. 36th Street Davie, FL 33314 http://sofia.usgs.gov/cacl/

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